Glossary of Technical Theatre Terms – Lighting (all)

(US) Originally shorthand for a lighting rig of 120 Parcans. This was a standard rig for big rock shows of the 1970s and early 80s. Nowadays, it refers to a rig of around 120 instruments, configured for a concert. But it may include any generic lanterns (but not moving lights etc.).

13A Plug - White Plastic (Toolstation) Standard domestic power connector in the UK. Three rectangular metal contacts (live, neutral and earth) with a fuse built-in (2A, 3A, 5A, 7A, 10A or 13A fuses are interchangable).

15A Plug - Duraplug Standard power connector in UK theatres. Three round metal contacts (live, neutral and earth); the principal difference from the domestic 13A connector is that the 15A version has no fuse.

A.J. / AJ
Adjustable Spanner / Wrench (Screwfix) n. Jargon for an Adjustable Spanner. (UK) Known in the US as a C Wrench (short for Crescent Wrench).

Lighting Industry Forum code which identifies the (original) recommended usage of different lamp types. A1 coded lamps are for use in projection. See also CP, T, P2, K.
Lamps List

ABTT Logo (from the ABTT website) (UK) The Association of British Theatre Technicians, which was formed in 1961 as a charity, to provide a forum for discussion among theatre technicians, architects and managers of all disciplines, and disseminate information of a technical nature, to all its members.
ABTT Website

Short for ALTERNATING CURRENT. An AC cord or cable is used to connect between a mains power socket and a piece of equipment.
A range of different connectors are used to connect to the equipment. The 3-contact IEC cable is common in Europe, and is sometimes known as a Kettle Lead. A figure 8 cable is used on smaller equipment which is double-insulated and has just two connections. Powercon is used on heavier duty equipment and locks into place to prevent accidental disconnection.

Lighting on a particular item or area on stage, to make it stand out or for aesthetic reasons, rather than to light an actor or functional area. Examples include lighting on specific architectural features on the set or in the theatre to make them 'pop' or because they're particularly significant. 

Additional equipment that adds functionality to a larger piece of equipment but which are not necessarily stored with (or sold with) the equipment. 
Accessories for a Fresnel stage lantern are a colour frame and a barn door. The Fresnel cannot function without a lamp or a power cable, so these aren't usually seen as accessories. 

ACL / A.C.L.
Acronym for AirCraft Landing Light. See AERO.

Stands for Architecture for Control Networks. A new (2003) ethernet-based control protocol between control desk, dimmers & moving lights. Developed by ESTA and Strand Lighting. DMX nodes are used to communicate with non-ethernet devices.

That area within the performance space within which the actor may move in full view of the audience. Also known as the playing area.
This term is also used to describe the smaller subdivisions of the main stage area which are lit separately by the lighting designer (e.g. 'The stage is split into 6 acting areas, 3 downstage and 3 upstage').
An Acting Area Rehearsal (also known as a Blocking Rehearsal) involves the actors running through their moves around the set, and less focus on the quality of the characterisation. 
(Also the name of an early Strand down-lighting floodlight - it was called an Acting Area Flood, and was colloquially known as 'Ack Ack' or 'A.A.').

1) Connector which allows two or more electrical devices to be connected to a single power outlet. The connection is normally parallel, that is, each device is fed the same voltage, but the current is divided between them. Sometimes known as a 'Twofer'. A three-way splitter is known as a 'Threefer'. A Series splitter is also available where a voltage is shared equally between two loads.
2) Also an ADAPTOR can be the same as a JUMPER.

(Manufacturer) Belgian manufacturer of lanterns, control desks and dimming equipment. Named after the initials of it's founder, Adrian de Backer.
ADB website

ADB 62.5
Near-obsolete digital lighting control protocol developed by ADB. Uses a 5 pin XLR connector but is NOT compatible with DMX512


(LIghting) Each item of equipment controlled by DMX512 has an address, which is the first DMX control channel to which it will respond. A dimmer rack requires 1 DMX channel per dimmer. A moving light requires many DMX channels.
For example, in a situation where you have three 6-way dimmer racks, the first should be addressed to 1, the second to 7 and the third to 13. Moving lights requiring 16 DMX channels each might be addressed to 120, 137, 154 etc.
The address is either set via pushbuttons (up / down) to get to the correct channel, via a menu screen, via small rotary selectors where you can set each digit of the address, or via DIP switches where each switch represents a binary digit which combine to give the full address.
In larger systems, where more than 512 channels are required, each block of 512 addresses is called a Universe. By default, Universe 1 is used, so DMX address 120 on Universe 1 is known as 1/120. 
Some control desks permit the use of absolute addresses, where the first address of the 2nd Universe, normally called 2/001, is numbered 513.

Adjustable Spanner / Wrench (Screwfix) See A.J.

(UK) Lighting bar positioned just downstage of the proscenium arch. Also known as ANTE PROSCENIUM (from Latin 'Before' or "In Front').

A gobo projected from a moving light or profile which is focussed into the air above the stage or audience, in order to add atmosphere and dimensional texture through smoke or haze in the venue.

PAR36 lamp, 28V, 250W with 25 hour lamp life A type of high intensity Par lamp that derives its name from its use as an aircraft landing lamp. The true Aero is 28V and 250W (type 4596), although there are many variations. The lamp has a very tight beam.

Formerly the ALD (Association of Lighting Designers), the association was renamed in mid 2021 to the Association of Lighting Production and Design (UK)
ALPD Website

Zero 88 Alphapack (DMX version) (Trade Name) Portable 3 way dimmer pack manufactured by Zero 88 in the UK. Integral faders to control the 3 dimmers. Maximum 6.3A load per dimmer. 
Zero 88 website

An electric current that reverses direction in a circuit at regular intervals. Abbreviated to AC. UK mains electricity is AC and changes direction 50 times per second (that is, the frequency is 50Hz).

A phenomenon seen when tungsten halogen lamps are dimmed which results in the light output becoming warmer (lower in colour temperature) as it becomes dimmer. LED lights maintain the same colour when dimmed, unless they have been designed to emulate the amber drift of tungsten light sources. 

The light in a venue with no stage-lighting sources switched on. Background light.

The standard unit for measurement of electrical current passing through a circuit (usually abbreviated to AMP). Written as 'I' in equations. Cables, fuses and switches are designated by their current carrying capacity.
(Following phrase refers to UK standards). Square pin plugs are rated at 13 Amps maximum and Round pin plugs at either 5 Amps or 15 Amps maximum, depending on the size of the pins. If a cable rated at 5 Amps is used with a load of 15 Amps (for example), the cable will overheat and possibly catch fire.


A continuously variable signal that can have any value over a given range.
1) In lighting: an analogue voltage within the range 0 to 10 Volts can have values of 0, 2, 8.785 or any value between. Most dimmers require an analogue voltage in order to operate (from 0 to -10V or 0 to +10V depending on the manufacturer). Most lighting control desks produce a digital multiplexed output, which is converted by a demux box to an analogue signal for the dimmer. See also Digital dimmer.
2) Sound: An analogue recording will record the exact waveform of the original sound, simply converting it to an electrical signal at the microphone, and back into air movement at the speaker. See DIGITAL.

Unit of measurement of length (e.g. for wavelengths of light). 1 Angstrom is equal to one ten billionth (1 x 10-10) of a metre. The unit is named after the Swedish physicist Anders J. Ångström.


American National Standards Institute. Three letter ANSI codes are used in the US to identify lamps.
ANSI website

Sometimes (incorrectly) called ANTI PROSCENIUM. From Latin - ANTE means in front of the proscenium. Refers to lighting bars or other equipment rigged in the theatre on the audience side of the proscenium arch. Often shortened to AP. 
Also known as FOH (front of house). 

(Manufacturer) US-based manufacturer of gel, gobos, effects and scrollers.
Apollo Design Technology Inc. website


(Trade Name) A coloured plastic tube containing a number of small strobe units which, when triggered, flash in sequence down the tube. Many tubes can be connected together.
Arc-Line in the Backstage Heritage Collection

A type of linear filament lamp with contacts at 90 degrees to the filament which can gives the appearance of a continuous line of light (similar to neon, but dimmable).

(Manufacturer) German/US manufacturer of film lighting and cameras (Arriflex). Founded in 1917. Previously, Arri made a range of lighting desks (including Imagine, Impulse, Mirage, Microlux) which were early versions of desks now produced by ETC. ETC took over the lighting control side of Arri in 1995.
ARRI website

Ethernet-based lighting control protocol, developed by Artistic Licence. ArtNet can carry up to 256 DMX512 universes on the ethernet saving on cable runs. With the development of wireless networking the possibilities are endless.
Art Net website

Short for Articulated Lorry. Lorries of 40 feet length (or more) are used to transport sets, costume, props and sound & lighting equipment from venue to venue. A number of companies specialise in moving theatrical and musical tours around the country / world.
Known in the USA as a SEMI (short for Semi-Trailer, where a trailer box with a rear axle only is pulled by a tractor unit). 

(Trade Name) Moving light control console made by Vari*Lite.
Vari*Lite Website

The controllable parameters of a colour-changing or moving light are known as the ATTRIBUTES.
All moving lights will have PAN and TILT, with many having COLOUR wheels, GOBO selection, gobo rotation etc. as additional attributes.
LEDs can operate in a number of modes, based on the number of colour sources they have, as well as whether certain parts of the beam can be separately controlled. A basic LED fixture might operate in 3 channel mode, with the 3 controllable parameters being RED, GREEN and BLUE. More complex fixtures might add AMBER and/or WHITE, and the latest LED fixtures may have LIME as well.


(Manufacturer) UK-based manufacturer of lighting control consoles (Azure, Pearl, Sapphire, Diamond) and dimmers.
Avolites website

American Wire Gauge. US system for measuring the thickness of wire. The lower the number, the thicker the wire.


A section of a lighting control board (sometimes a separate unit) which provides an alternative method of control should the main board fail.

Light coming from upstage, behind scenery or actors, to sculpt and separate them from the background.
Any kind of lantern can be used for backlighting, but commonly Fresnels or PCs are used, and sometimes Parcans. 
Moving LED washlights are extremely popular for backlighting, as they can be easily refocussed and coloured to match the scene. 
See also TOPLIGHT.

1) A sheet of material used to prevent a spill of light in a lantern or in part of a set.
2) A panel in a loudspeaker cabinet designed to reduce back interference noise by isolating the front and rear of the loudspeaker diaphragm.
3) A panel in an auditorium positioned so as to reduce sound reflections and improve the acoustics of the space.
4) What most of this jargon will do to any non-technical theatrical type.

(Trade Name) Early type of thermosetting plastic often used for electrical plugs and sockets. Has a distinctive fishy (ammonia) smell when burning.


A unit used in conjunction with discharge lamps containing capacitors, inductors and other start-up circuitry. The inductor is initially used to develop a high potential (voltage) to strike the discharge and is then used to limit the current flow while the lamp is lit.

(US) Swinging a followspot beam around in a figure of eight pattern. A more random effect is sometimes known as an RKO (after the searchlights used in the RKO Pictures movie logo.

4mm Banana Plugs ( Plastic bodied single-connection plug used on some test meters and audio equipment. 

The horizontal metal (steel or alloy) tube (usually 48mm in external diameter, but can be up to 60mm) hung from flying lines (or forming part of a grid) from which lighting equipment and scenery etc. may be suspended. Also known as a BARREL. When vertical, known as a BOOM. Sometimes known as a PIPE in the US, although many curse that usage, and demand the use of Batten ; 'A pipe is what you smoke; a batten is what you hang your instruments from.'
Language, especially in theatre, is rarely universal! In German, ZUGSTANGE.
Many lighting bars are internally wired (and are known as IWBs or Internally-Wired Bars), featuring cabling inside the bar and sockets mounted at regular intervals along the bar, and a connection box at one end to enable the bar to be plugged into dimmers. Lighting bars nowadays need 'hot power' sockets and DMX outlets, as well as the more usual dimmer output sockets into which traditional theatre lighting equipment is connected. 

Term to describe an electrical cable which has no connector at one end (for example, a SPEAKON to BARE ENDS cable is used to connect the terminals of a speaker cabinet to a speakon socket, and a 63A socket to bare ends might be used to wire in a temporary supply from a power distribution board before connecting equipment. Any installation work of this sort should only be carried out by a qualified electrician, and should never be done 'live'.

Barndoors on Strand Harmony Fresnel A rotatable attachment consisting of two or four metal flaps (hinged) which is fixed to the front of a Fresnel or PC type lantern to cut off the beam in a particular direction(s).
Profile lanterns use SHUTTERS to achieve a greater degree of control and accuracy.
Barndoors are also available for parcans and birdies. BLACKWRAP can be used to reduce additional light spill where barndoors aren't doing the job.

See BAR.

Scaffolding Base Plate A metal plate which prevents damage to floors when using scaffolding or trussing.

1) Timber at the top and bottom of a cloth. A Sandwich batten is used to carry a hanging cloth. It comprises two flat pieces of timber screwed together with the edge of the cloth between them.
2) Timber used for joining flats together for flying.
3) Compartmentalised floodlights set up to allow colour mixing. See also GROUNDROW. Low voltage battens are commonly used as light curtains & for colour washes. Known in the US as a STRIPLIGHT, BORDER LIGHT or X-LIGHTS. 
4) US term interchangable with PIPE for a flying bar.

(Bits per second) Measurement of the speed of electronic communications protocols. DMX512 operates at 250,000 baud (i.e. 250,000 electronic signal changes per second).

Type of UK domestic lampholder that has largely been replaced by the ES (Edison Screw) and the GES (Goliath Edison Screw) for general lighting applications in the theatre. Stage lighting equipment uses prefocus lamp bases. (Most types of Festoon still use BC holders.)

The angle of the cone of light produced by a lantern.
The Field Angle is a measurement of the width of the cone of light produced by the lantern until the light falls off to 10% intensity. This is a wider angle then the Beam Angle, which is a measurement of the cone of light until the light falls off to 50% of full intensity. 
For a sharply focussed profile, the Field angle and the Beam angle will be very similar (or identical). For a Fresnel or Parcan, there will be a difference between the two. It's best to use Beam Angle when calculating lantern coverage.

Strand Lighting Beamlite Lensless lantern which uses a parabolic reflector and a low voltage high intensity lamp to produce an intense near-parallel beam. Also known as a Beam Projector.
A PARCAN is a special type of beamlight.
Beamlite in the Backstage Heritage Collection

Broadcasting, Entertainment, Cinematograph and Theatre Union. The UK entertainment technicians union. (US equivalent is IATSE)
BECTU website

A call given by Stage Management to bring those actors who appear in the first part of a play to the stage. e.g. "Act One Beginners to the stage, please". The actors are then called by name.
A similar call is given after the interval (e.g. "Act Two Beginners to the stage please").
The call is usually given 5 minutes before the advertised performance start time, but this may vary depending on how long the actors take to get into position.
See Calls and Cans

Part of the communication ('cans') system in a theatre, the Beltpack contains the controls and circuitry to drive the HEADSET worn by crew members. Each beltpack connects into the headset ring and back to a PSU (Power Supply Unit) which is powered from the mains.
See also CANS.

The process of adjusting the lamp and reflector positions on a profile lantern such as the ETC Source 4 to ensure a smooth and even beam. 

Zero 88 Betapack 3 (Trade Name) Portable 6 way dimmer pack manufactured in the UK by Zero88.
Zero 88 website

Profile lantern with two sets of shutters, one of which produces a hard edge, and one a soft edge. Not necessary in zoom profiles, because this requirement is fulfilled by two lenses.
The first theatre lantern with this functionality was the Patt.264. The T-Spot range also had bifocal shuttering. 
Patt.264 in the Backstage Heritage Collection
T Spot (1976)

BIT = Binary Digit. More information coming soon.

(Aus) Australian term for the lighting / projection control booth at the rear of the auditorium. Shortened version of BIOGRAPH BOX, after it's original function as a cinema projection box. Sometimes also known as the DOME if followspots are controlled from the same position.

(Lighting) Describes a fllament inside a lamp which has two sections, a front and a back filament, which enables more light to be produced from a smaller point than with a monoplane filament.

MR16 Birdie A compact low voltage display luminaire containing a Par 16 or MR16 lamp. So called because it is similar to, but much smaller than, the Parcan, and is hence "one under Par". (In golf terminology, a birdie is a score one below the par for that particular hole).
Low voltage birdies require a 12 Volt external transformer. Mains voltage birdies are also available.
Due to its compactness, the birdie is ideal for concealing in pieces of set or as downstage uplights. The beam angle can be narrow - a range of different lamps are available with differing beam widths.
See also MR16.
Types of Lantern

An accidentally unlit portion of the stage.


1) Complete absence of stage lighting. Blue working lights backstage should remain on and are not usually under the control of the board, except during a Dead Blackout (DBO), when there is no onstage light. Exit signs and other emergency lighting must remain on at all times.
2) The act of turning off (or fading out) stage lighting (e.g. "This is where we go to blackout")
3) Blackout Check (or Dark Check) takes place in some multi-purpose venues to ensure that window curtains or blinds are closed and that there is no stray light either from adjacent rooms or the outside world, before the audience is admitted. 

Blackwrap Roll from GAM (24 inch x 25 feet roll) (Trade Name) Thin black aluminium product which is used to temporarily mask light coming out of a luminaire's body, or to control spill. A self-adhesive tape version is also available.

Trade name for a type of low voltage 8 pin connector which is similar to the audio DIN plug. Used most often for carrying signals from analogue lighting control desks to dimmers or to demux boxes. Originally manufactured by Belling and Lee, hence BLEEcon (for connector).

1) Dimmers which are incorrectly trimmed are said to bleed. That is, the dimmer still gives a small output, causing the lantern to glow, when the control signal is at a minimum.
2) A contrasting colour paint still showing through a newly-applied top coat is said to be bleeding.
3) A transformation from in front of a gauze to a previously unseen scene behind it is called a 'bleed-through'.

Transformation from a scene downstage of a gauze to another scene upstage, by slowly crossfading lighting from downstage to upstage. If a gauze is lit steeply, or from the sides, it will appear solid. If this light is turned off and light added to the set upstage of it, it will disappear.

The facility on some lighting control desks for the operator to make changes to the stored lighting cues without affecting the state on stage. 
Pressing the BLIND button leaves the current state on stage, and can instantly update other cues as required. Once you are finished, pressing LIVE will return to normal operation. 

1) Lamps arranged around the stage directed into the auditorium, originally to prevent spectators seeing the stage during scene changes when the house tabs were not lowered. Now used for effect in rock concerts etc.
2) A strip of dense black material fastened behind a crack between two flats or scenic pieces to prevent light leak. Cloth hung behind a gauze to prevent transparency before the effect is required.

2000W open-faced flood lamp used in film / TV lighting. So-called because of it's yellow/gold paint finish. See also REDHEAD.

Chromatic effects at the sharply-focussed edges of the beam from a profile lantern. The focus can be adjusted to give either a blue effect or a brown effect - the lighting designer can decide which is the option they want to go with. The effect is also seen when using gobos. Sometimes the effect can be reduced by using a DONUT to sharpen the image.

(Lighting) A fade to blue backlight only. Better than a full blackout, especially if the scene change is well choreographed.

Blue lights used backstage in a performance situation. See also working lights.

Bluetooth Logo A technology enabling devices to wirelessly connect together over a short range for the purposes of playing or recording sound, or transferring data, or controlling a fixed device with a mobile device (e.g. mouse / keyboard).

BNC Connectors on black coaxial cable (from Coaxial connector used for carrying a composite video signal or radio frequency signal. BNC stands for Bayonet Neill Concelman - after original inventors Carl Concelman and Paul Neill who developed the connector in the late 1940s. BNC is also thought to stand for 'Bayonet Nut Connector'.
See also TNC.

The main control for the stage lighting. Originally known as the switchboard or dimmerboard, it is now usually remote from the dimmers. The lighting operator for a show is said to be "on the board", and is sometimes known as the "board op". In the US, the board operator is said to be "running the lights".
Known in the US as the Light Board. Also known as the Lighting Desk, LX desk, control desk, lighting console.
The links below take you through 3 generations of lighting control - initially directly controlling the dimmers using large levers, then remote operation using manual faders, then the current generation of computerised controls where lighting states are recalled at the touch of a button or the click of a mouse. 
Direct Lighting Controls on Backstage Heritage Collection
Manual Lighting Controls on Backstage Heritage Collection
Memory Lighting Controls on Backstage Heritage Collection

Metal bin or box covered with fine mesh in which Theatrical Maroons can be safely detonated.

Boom Arm (Doughty Engineering) 1) Vertical scaffolding pole (usually 48mm diameter) on which horizontal boom arms (also known as sidearms or de-rig arms) can be mounted, carrying lanterns. Often used behind wings for side-lighting etc. Booms have a base plate (known as a TANK TRAP) or boom stand at the bottom and are tied off to the grid or fly floor at the top (not always necessary for short booms). Booms can also be fixed to the rear of the proscenium arch (Pros. Boom) or hanging from the ends of lighting bars. Sometimes known in the US as a LIGHT TREE. A light tree mounted upstage of a Tormentor is known as a Torm Tree. A boom used in the wings for dance lighting is sometimes known as a BALLET BOOM (which consists of 3 lanterns on each boom, at shin height, waist height, and head height, known as SHINS, MIDS and HEADS). 
2) An arm mounted on a microphone stand.
3) A long lightweight support for a directional microphone used to capture dialogue in TV/Film production. 
Boom Arms - Doughty Engineering (UK)


Tank Trap / Boom Base made by Doughty Engineering A wooden board or heavy-duty metal panel with vertical scaffold tube adaptor used as a base for lighting booms. Although the base provides a degree of support (especially with added brace weights) booms often require additional support from above.
See also Tank Trap, which is a purpose-made all-metal boom base. 

2) Old name for a BOOM (vertical lighting position).

(US) Control Room.

A narrow horizontal masking piece (flattage or cloth), normally of neutral colour (black) to mask the lighting rig and flown scenery from the audience, and to provide an upper limit to the scene. Often used in conjunction with LEGS.
In part of the 20th century, borders were made from asbestos materials, but are now made from fire-retardant cloth (e.g. Wool Serge). 
Spanish: Bambolina

1) Diffuse light that has been reflected from the stage, walls, cyclorama etc.
2) 'Bounce' is sometimes used for a flat (non-curved) cyclorama. Strictly, a bounce is a white or light blue cloth onto which light is bounced to backlight another cloth. A bounce doesn't need to be seamless, whereas a cyclorama should be.
3) Film/TV: A large piece of white material / board which is used to bounce and diffuse light towards actors on a film/tv set. 
4) Describes the fast in/out movement of 'bouncing' flown house tabs, traditionally used during curtain calls. This can also apply to the fast blackout/lights up cues that happen at curtain calls. When taking curtain calls, the Stage Manager would instruct the head flyman 'On the Bounce Please' for all calls prior to the final call, which was always 'Hand over Hand', i.e. slowly.
5) This facility was available on many multitrack tape machines. Describes the mixing down of multiple sounds from different tracks onto one track, hence freeing up the other tracks to be re-used. It allowed many sounds to be recorded onto one tape. The term now refers to the digital equivalent - taking multiple audio tracks and mixing them together at their set levels onto a single (pair of) tracks. 

When scenery prevents you safely getting access equipment under a lighting position, you may need to bounce focus the instruments on that bar. This involves flying the bar to a reachable height, turning the lantern on, adjusting the tilt / focus, flying it out to the 'dead' height, and seeing whether it does the correct job. If not, continue flying it in and adjusting until it's correct. 
Although time-consuming, this is sometimes the only way. 
Some touring companies use FOCUS CLOTHs covered in odd shapes and markings so that the instruments can be focussed to the cloth markings, then flown out, and they will look correct.  

Short for Bowens Flash Unit. Instrument which produces a bright white flash when triggered. Used by professional photographers. Unlike a STROBE, the Bowens unit needs to charge up between flashes (around 10 seconds) so is unsuitable for the same applications, but is ideally suited for recreating bright lightning flashes on stage.

1) Lighting Box - see CONTROL ROOM.
2) Enclosed seating area at the side of the auditorium in a traditional proscenium arch theatre. In the UK, some London theatres have a ROYAL BOX, which is usually equipped with an additional private reception room and is available for members of the Royal family (or other VIPs) to use. 

US term for a front of house vertical lighting position (predominantly sidelight as the booms are rigged from the boxes nearest the proscenium arch).


A horizontal rope, wire or chain attached at either end of a piece of scenery or lighting bar pulling it upstage or downstage of its naturally hanging position to allow another flying item to pass, or to improve its position. See also BREAST LINE.
In a hemp house, to 'Brail' a static piece a single dead line was put round the 'short' and 'long' line to move the piece to a new position. A running brail was a breast which allowed the flown piece still to fly in or out, in its new position.

15m 8 way Microphone Multicore cable with breakout box (from A connection at the end of a multicore cable which allows the connection of many items to it. (e.g. there is a breakout box at the end of a sound multicore cable which allows you to plug microphone cables into it).

A commonly used abstract GOBO which gives a textured effect to the light, without throwing a specific pattern onto the stage. Used to add interest to light beams. A leafy breakup is used for outdoor scenes / forests / spooky wood etc. to break up the light on the actors faces.

1) A walkway, giving access to technical and service areas above the stage or auditorium, or linking fly-floors.
See also CATWALK.
2) A lighting position above the auditorium, commonly with a catwalk above it to access lighting equipment and electrical systems is known in Dutch as a Zaalbrug.
3) A section within a song which provides a break from the previous verse / chorus, to prepare for the final chorus or climax, and can also provide a contrast with the previous lyrical tone or style.

A measure of the amount of light produced by a display screen, projector or light source.
Data projector brightness is measured in lumens. A lumen is a measure of the brightness of a light source.
One lux is one lumen per square meter. One lumen is one candela per square radian (to measure the light travelling outwards from a light source).
Cinema screen brightness is measured in nits. A nit is unit of visible-light intensity, commonly used to specify the brightness of a cathode ray tube or liquid crystal display computer display. One nit is equivalent to one candela per square metre.

British Standards Institute.

1) (especially TV and Film) Jargon for a replacement lamp.
2) The glass part of a lamp, also known as the ENVELOPE.
See also GLOBE, LAMP.

1) During lighting plotting, to construct a state from blackout, or to add to an existing state.
2) An increase in light or sound level. See CHECK.
3) A period of set construction ('The Build').


Range of connectors used for multipin or 'non-standard' connections. The small 3 pin Bulgin plug is used on the Le Maitre Pyroflash system. The larger 8-pin round 'truck plug' allows the connection of 6 dimmer circuits (up to 6A each) via a single multicore cable. This is ideal for carrying multiple dimmed circuits to a moving set-piece or truck. The 8-pin round connector has become a standard for disco lighting systems.
Bulgin Components website

A flash or sudden jump in light level (a snap cue) (see also FLASH BUTTON).

A lighting cue that instantly bumps the lighting up to a brighter level (a time of 0 seconds). Usually at the end of a musical number to draw the applause. The bump cue is sometimes called a 'button'. 

A coloured gel that has lost its colour or melted through due to excessive heat in front of a lantern. Dark blues and greens etc. are most susceptible, and may need replacing during a long run.

Metal bar carrying incoming electrical supply into which portable dimmer racks or other large power requirements can be wired directly. An enclosure containing busbars is a Busbar Chamber.

1) For lighting operators / designers: Busking is when the lighting looks for each part of the show (usually a live music gig) are created spontaneously in response to the performance. Very often, basic palettes, states and effects are loaded onto preset faders, and combined by the operator during the show. Allows a very fluid performance and gives the lighting designer / operator a great deal of control about how the show looks, but is not repeatable. Busking would normally only happen for a one-off performance where the amount of time to pre-programme a series of states and sequences is not necessary or possible given tight timelines.  
2) For musicians in the UK: Busking is performing music in a non-performance venue (e.g. on the street) with a way of passing members of the public donating cash. 

C Clamp (ETC) US equivalent of the UK Hook Clamp. Requires a spanner/wrench to tighten. Known as a PARROT CLAMP in the US film business.

Calumet 2.6m C-Stand Also known as a Grip Stand. The C Stand is a 3 legged heavy duty stand used for holding lighting accessories on a film set. C Stands are not typically used for luminaires - instead they hold reflectors and flags to cut off and reflect light. However, they can be used to support smaller (e.g. LED) light sources. While normal C Stands can't be folded, they do nest and can be stored ready to use in the corner of a studio or stage. 
The C stands for Century Lighting, who made a range of film & theatre lighting equipment (later becoming Century Strand and then Strand Lighting). 

US for SPANNER. (Abbreviation of Crescent Wrench).

Wiring, temporarily rigged, to carry electrical current. Depending on the size of the cable (current carrying capacity), cables are used to supply individual lanterns, whole dimmer racks, or carry signals from a microphone etc.

A U-shaped clip and saddle used for terminating wire rope. Also known as a Bulldog, Dog Grip or Wire Rope Clip.

Pyle Cable Tester A tool designed to check connections and terminations on a range of cables used in audio, lighting and audio-visual applications. 

Lockable (and sometimes releasable) plastic strap used to tie a bundle of cables together, amongst many other things.
Cable ties are absolutely not to be used to suspend anything (of any size, or at any height). Also known as Zip Ties.

Computer-Aided Design. Using a computer to help with 2D plans and drawings, or increasingly for 3D visualisation of how a set will look, and how lighting will affect it. See also WYSIWYG.

Cadenza range of 2000W Lanterns by Strand Lighting Range of 2000W lanterns by Strand Lighting in the UK. 
Cadenza in the Backstage Heritage Collection archive

1) A notification of a working session (eg a Rehearsal Call, Band Call, Photo Call, Focus Call). A rehearsal call for the next day / week used to be posted on a Call Sheet on the stage door noticeboard, but is now often an online document, updated by the stage management team. A 'Company Call' means the full cast and crew are called for the rehearsal. 
2) The period of time to which the above call refers. (eg "Your call for tomorrow nights show is 6.55pm")
3) A request for an actor to come to the stage because an entrance is imminent (these are courtesy calls and should not be relied on by actors - eg "This is your call for the finale Mr Smith and Miss Jones")
4) An acknowledgement of applause (eg Curtain Call)
5) The DSM on the book is said to be "calling the cues".
6) The Colour Call is a list of lighting gel required for the lighting rig.
7) The Final Call is also known as The Half - 35 minutes before the performance starts, and the latest time when the cast and crew should be in the theatre.

The process of giving verbal cues to the lighting, sound, fly operators and stage crew during the performance. Usually done from the prompt corner by the DSM on the book or Stage Manager over cans.
Being 'on the book' involves verbally giving the 'GO' cues to all technical departments (lighting, sound, flies, automation, av etc). The cues are written in the prompt script. A 'STANDBY' (UK) or 'WARN' (US) cue is given first, so that the operators are ready for the actual cue.

(Trade Name - Crouse Hinds - CAMLOK) Single pole connector used on professional power distribution & dimming systems. A separate connector is used for each phase/neutral of the supply.Originally developed for touring concerts, as power demands increase it's finding more use in theatres.

1) Headset earpiece, microphone and beltpack used for communication and co-ordination of technical departments during a performance. (e.g. "Electrics on cans", "Going off cans", "Quiet on cans!").
A commonly used system in the UK is produced by Canford Audio under the TecPro brand. In the USA, ClearCom is commonly used.
As many of the technical operators are tied to expensive pieces of equipment, headsets are often wired. However, stage management (and any other crew who move around) often wear wireless versions, often known as radio cans. There are interfaces between wired and wireless versions enabling both to be part of the same system.
Many headset systems have multiple channels, enabling different sub-groups to communicate separately.
[Named after the well-known usage of two tin cans connected by a piece of string being able to transmit and receive a sound mechanically].
Also called 'Comms' short for Communications - the same phrases can be used (e.g. 'LX Off Comms' when leaving the operating position).
See link below for Cans Etiquette.
2) Any headphones.
3) Short for PARCANs.
Calls and Cans

(Trade Name) Range of 1200W lanterns produced by Rank Strand (now Strand Lighting) in the UK.
Strand Lighting website
Strand Archive

First demonstrated by Humphrey Davey in the early 1800s, the carbon arc lamp was the first practical electric light. It consisted of two carbon rods in air connected to a power source. To ignite the lamp, the rods are touched together and then slowly drawn apart. The electric current heats the tips of the rods and maintains an arc (originally, an 'arch' of electricity). The carbon at the tips of the rods vapourises, producing an intense bright light. The rods are slowly burnt away in use so constant adjustment of the distance between the rods is necessary to maintain the arc.

Circular slide magazine; also refers to a 35mm slide projector using this type of magazine (Kodak trade name). See PROJECTION.

Canadian creators of WYSIWYG software.
Cast Lighting website

Part-time temporary technicians (paid by the hour).

Closed Circuit television. A video relay system, used in the theatre to give a view of the stage to remote technical operators (especially stage managers). Also used to give musical performers a view of the conductor (and vice versa) to help in keeping time. It's called Closed Circuit because the signal is not being broadcast anywhere - there's a direct link between camera and monitor.

(UK / Europe) A range of standard plugs & sockets for power, which are IP rated for outdoor use.
They come in a variety of sizes and colours. Blue is 230V, Red is 415V (3 phase).
Sizes available include 16A, 32A, 63A and 125A. These refer to the current-carrying capacity of the connector.

Manually operated or electrically driven hoist for lifting scenery and lighting equipment. The chain hoists are rigged to fixed points in the venue. Commonly used to lift lighting truss into position for touring shows or concerts.

A complete control path for signals in lighting or sound equipment.
In a lighting desk, the channels are directly controllable by the lighting operator. Within the desk, the channels are 'patched' to a dimmer or dimmers which the desk then sends a signal to depending on the level of the channel.
On a sound desk, the channels typically refer to a particular input or output path, and on digital sound desks can be configured in whichever way is appropriate for the event being set up. 

Lighting: Function on ETC lighting consoles which flashes a channel to 100% if it is at or below 50% or down to zero if it's above 50%. 

A repeated sequence of changing lighting states. A chase can be produced easily by the effects functions of a computerised lighting desk. There are standalone units designed to chase lighting circuits electronically in time to music (sound to light) or mechanically as a repeated sequence (as used in early neon signs).

A smaller version of the lighting plan, used by the lighting designer during the lighting plot. Also known as a Dimmer Layout or Magic Sheet.
Lighting control software can produce an electronic version of the Magic Sheet, which can be laid out however works best for the lighting designer, and provides shortcuts to groups of lanterns, effects and colours.

1) Opposite of Build; a smooth diminishment of light or sound level (e.g. Lighting: 'I think we should check this state down a touch as the song begins')
2) See Prefade Listen.

(n.) In Lighting or Scenic design (and the Art world), Chiaroscuro means the use of contrasts of light and shade, especially in order to enhance the depiction of character and for general dramatic effect. Many painters are said to be masters of Chiaroscuro (especially Rembrandt, Caravaggio etc.) From the Italian words chiaro 'clear, bright' and oscuro 'dark'. From the Random House Word of the Day website.

The senior member of the theatre's stage lighting team, although not necessarily the lighting designer. Known in the US as MASTER ELECTRICIAN.
In common with many theatre jobs, the actual duties of the Chief Electrician vary from theatre to theatre. Some chiefs are responsible for electrical maintenance of the building, some design the lighting for nearly every in-house production, some design no lighting at all, some have a team of eight staff under them, some have two. Many theatres employ casual staff to assist on lighting rigging sessions. Some theatres have a separate sound department, smaller venues have the lighting team also running sound for shows (and doing sound design for some).
Abbreviated to CLX in some UK venues.

Usually white, wax-based pencil used for marking magnetic tape prior to splicing. Also used for marking identifying numbers on lighting gels.

(Followspot term) Two horizontal masking shutters used in followspots to shape the beam above and below.
Submitted by Bert Morris.

(Compact Iodide Daylight) A high intensity discharge lamp that produces a light similar in colour temperature to daylight approx. 5500K). A 1000W CID lamp produces 2.5 times more light than a 2000W tungsten halogen source.

(Commission Internationale d'Eclairage) International lighting forum which has produced (amongst many other things) a series of universally recognised symbols for lighting plans.
CIE website

Now obsolete term for lighting colour gel, produced by Rank Strand / Strand Electric in the UK. A much thicker (and less flexible) gel than that produced nowadays.

Circle Fronts at Theatre Royal Drury Lane, January 2019 (before the refurbishment began) A permanent front of house lighting position in older proscenium theatres. A number of spotlights, sometimes fitted with colour changers, are recessed into the front of the circle balcony above the stalls. Sometimes known as the Balcony Rail position.

1) The means by which a lantern is connected to a dimmer or patch panel. Numbered for reference. In a fully patchable system, the circuit number (also known as socket number) can be connected to any of a wide range of dimmers. 
The process of allocating circuits to dimmers is sometimes known as circuiting. The process of connecting lanterns to dimmers is sometimes known as plugging up. Abbreviated to 'cct'.
2) A complete electrical 'loop' around which current can flow.

An electro-mechanical 'fuse' that can be reset, rather than having to be replaced when too much electrical current flows through a circuit.
Available in the same ratings as fuses.

Canadian Institute for Theatre Technology.
CITT website

Long-running column in Lighting & Sound International magazine, by Rob Halliday, discovering the history and origins of many essential technologies and bits of equipment that have made entertainment technology what it is today. 
See the Lighting & Sound International archive for many examples. 

Auditorium working lights. Used for cleaning and setting up the auditorium before the house lights (usually more atmospheric) are switched on.

Invaluable hitch that every technician should know.

Cyan / Magenta / Yellow - the three secondary (additive) colours of light which are used in moving lights for colour mixing. Some cheaper systems use three graduated colour scrolls (one of each colour) in front of a standard fixture, but these take a massive amount of intensity out of the beam, resulting in a dim light on stage. Many moving lights use a similar system with dichroic colours which are more efficient and longer-lasting.



1) A list compiled from the lighting plan of all the colours needed for the rig, and their size. This term also applies to the act of preparing colour filters and frames from such a listing.
2) A colour scroller made by Strand Lighting
Lighting Paperwork
Strand Lighting Colour Call scroller

1) Scroller, where a long string of up to 16 colours is passed horizontally in front of a lantern. Remotely controlled by the lighting desk. Some scrollers have cooling fans to prolong the life of the gel string. Stronger colours will burn out faster without cooling, or if the focus of the beam is concentrated on the gel. If colours aren't lasting very long in scrollers, try changing the focus of the lantern. HEAT SHIELD clear gel should be used between the lens and the colour scroller to absorb some of the heat.
2) Wheel : Electrically or manually operated disc which is fitted to the front of a lantern with several apertures holding different colour filters which can be selected to enable colour changes. Can also be selected to run continuously.
3) Semaphore, where framed colours are electrically lowered into place in front of the lantern. Remotely controllable. Can perform additive colour mixing by lowering two colours into position at the same time.
4) Magazine : Manual semaphore-type device used on the front of a followspot. Known in the USA as a BOOMERANG.
Colour Changers at the Backstage Heritage Collection

The use of colour filters to compensate for the different colour temperatures of different light sources. Important in lighting for TV and film.

A sheet of plastic usually composed of a coloured resin sandwiched between two clear pieces. The coloured filter absorbs all the colours of light except the colour of the filter itself, which it allows through. For this reason, denser colours get very hot, and can burn out very quickly.
There are a number of manufacturers of Colour Filters - Lee (UK), Rosco (US), Gam (Great American Market - US) and Apollo (US) are some of the more popular. Each manufacturer's range has a numbering system for the different colours. It's important to specify which range you're talking about when quoting numbers.
A colour filter is sometimes known as a Gel, after the animal material Gelatine, from which filters were originally made.
A colour frame is used to hold the colour filter, which slots into the colour runners in front of the lens of the lantern, just behind the barndoors (for a Fresnel or PC).
A range of specialised gels are available for non-standard purposes, including:
Neutral Density Filters - these are tinted grey, and while they don't produce grey 'colour' light (which is impossible) they do reduce the brightness of the light, without affecting the colour. They are used in TV/film on windows to cut down on natural light. 
Frosts - These are used to soften the sharp focussed edge of the beam of a profile lantern, or to smooth over any unevenness on any other beam. 

A selection of gel frames (c) (or Gel Frame) A frame which holds the colour filter in the guides at the front of a lantern / lens tube.
Many different sizes of frames are needed for different lanterns.

Combining the effects of two or more lighting gels:
1) Additive : Focusing two differently coloured beams of light onto the same area (eg Cyc Floods). Combining colours in this way adds the colours together, eventually arriving at white. The three primary colours additively mix to form white, as do the complementary colours.
2) Subtractive : Placing two different gels in front of the same lantern. Subtractive mixing is used to obtain a colour effect that is not available from stock or from manufacturers. Because the ranges of colour are so wide, the need for subtractive mixing is reducing. Combining colours in this way reduces the light towards blackness. The three primary colours mix subtractively to form black (or to block all the light).
More on Colour Mixing

Electronic lighting controller which automatically varied the intensity of lighting equipment in time to music. Often used 3 channels (Treble, Mid, Bass) and a single audio input. Each channel had a rating in watts based on what the dimmer circuitry could handle. There was often a controller for adjusting the sensitivity of the dimmer to the sound input. 
See also Light Console (early lighting control system based on a Compton organ console)

A set of metal guides in front of the lens of a lantern into which a colour frame is slotted, containing a colour filter or gel. The colour runners are sometimes used to hold barndoors (or other accessories including colour scrollers) at the front of a lantern, and sometimes these accessories fit onto the lantern using a different method.

Rainbow Colour Scroller (from GearSourceEurope) See COLOUR CHANGER.

A measure of the 'warmth' or 'coolness' of light sources and colours. Measured in degrees Kelvin. A higher colour temperature light source will appear whiter (colder). The human brain automatically compensates for different colour temperatures - a film or video camera cannot, and thus what we see as white may appear to have a blue or green tint when no colour correction is used for video. Most video cameras have a 'White Balance' control to make colour temperature adjustments, to ensure white looks white on camera.
Daylight is approximately 5600°K, Tungsten Halogen is approx. 3200°K and standard incandescent lamps are 2800°K. Many discharge light sources are in use in modern theatrical productions using discharge followspots or moving lights - colour correction filters are used to balance the colour temperatures.

The science behind the way colour works can help lighting, costume and set designers to make their work as vibrant (or dull) as the play requires. See the link below for information. 
Choosing and Using Colour

CCT Colour Wheel on Sil Profile See COLOUR CHANGER.

Warning used when flying scenery or lighting bars (electrics). 
e.g. "First Electric Coming In", "Heads on Stage - LX3 coming in!" etc.

Pairs of colours which, when additively mixed, combine to produce white light. Examples are red + cyan, green + magenta, and yellow + blue.


Lens shape. Edges are wider than the centre of the lens. Useful to remember that 'caves' go inward.

Loosely applied to any spotlight lens which condenses diverging rays into a beam, but more correctly to the short focus combination of two or more lenses in a jacket used for illuminating a slide or effect disc. Also used in some profile lanterns and followspots to produce a smoother light (especially for gobo work).

Metal or plastic pipe used to carry electrical conductors as part of a permanent electrical installation. See also Trunking.
Also used to add weight to the bottom of a flown cloth.

Room at the rear of the auditorium (in a proscenium theatre) where lighting and sometimes sound is operated from. Known in the US as the BOOTH. The stage manager calling the cues is very often at the side of the stage (traditionally stage left) but in some venues they may be in the control room also. The control room is usually soundproofed from the auditorium so that communications between operators cannot be heard by the audience. A large viewing window is obviously essential, as is a show relay system so that the performance can be heard by the operators. Obviously if sound is being mixed, the operator should be able to hear the same as the audience, so some control rooms have sliding or removable windows, or a completely separate room for sound mixing. Where possible, the sound desk is moved into the auditorium so that the operator can hear the same as the audience.
Also known as the BOX.

Standard stage lighting instruments, rather than moving lights, LEDs or other effects. (e.g. 'There are 40 instruments in the rig - 20 moving lights and 20 conventionals'). 

Lens shape. Edges are thinner than the centre of the lens.



Scaffold Double Coupler (Doughty Engineering) Equipment used to join two other items together.
Commonly refers to a SCAFFOLD COUPLER (also known as a SCAFFOLD CLAMP or TUBE CLAMP).
A scaffold clamp is known as a Cheeseborough in the USA, believed to be named after Chesebro-Whitman Company of New York City. 

US for front of house catwalk lighting positions. Also 'Balcony Rail'.

Lighting that does a particular job during the show. (e.g. GENERAL COVER is the main actor light on stage, UPSTAGE COVER lights that area etc.)

Lighting Industry Forum code which identifies the (original) recommended usage of different lamp types. CP coded lamps are for Film, Television and Photographic studio use and have a colour temperature of 3200°K. See also A1, T, P2, K.
Lamps List

A smoke effect which creates a haze in the air to make light beams visible. This effect is rarely used now, because it has been found to be carcinogenic. See Water Cracker.

Adjustable Crescent Wrench (Wikipedia) (US) A open ended adjustable hand wrench originally produced by the Crescent Tool Co. Known as a C-WRENCH.

Abbreviation for Colour Rendering Index.
A measure of the ability of a light source to reveal the colours of objects faithfully in comparison with an ideal or natural light source. A CRI of 100 for a white light source is equivalent to tungsten light, and is seen as giving an excellent rendering of colour across the spectrum.
Wikipedia entry

Wireless DMX Protocol. Used by LumenRadio and Astera products. 

Crosby Forged Wire Rope Clip (Red U Bolt Clip, from the Crosby website) Manufacturer of shackles and lifting hardware (US, Canada and Belgium). The shackles are known as Crosby Clips. 
Crosby Group website

Bringing a new lighting state up whilst bringing the previous one down, so that the new one completely replaces the old one. Also applies to sound effects / music. Sometimes abbreviated to Xfade or XF.
A DIPLESS CROSSFADE occurs when the lighting doesn't dip significantly between states, which results in a more subtle transition.
Some sound mixers (especially those for DJs) have a cross-fader - a single fader which can be used to fade one music source out while simultaneously fading the next one in.

Light coming from the sides of the stage towards the centre (i.e. across the stage). Used heavily for dance lighting as it lights the body of the performer without casting shadows upstage, and it is far more sculptural than front light. Also used for additional atmosphere in many other types of performance. 

Type of lamp which has the top part of the envelope / bubble silvered so that the light is reflected backwards (where the reflector of the light fitting / lantern will reflect it forwards). Used in beamlights and other narrow-angle fittings to help produce a near-parallel beam, without glare from the lamp.

(Compact Source Iodide) A high intensity discharge lamp. Most often used in followspots, because it has a colour temperature (approx. 4000K) close to that of the tungsten halogen lamps.

Colour Temperature Blue - a colour filter to convert a warm light source to a colder colour to match daylight or to match discharge light sources.
See also CTO.

Colour Temperature Orange - a colour filter to correct a cold discharge or LED light source to be more warm, or on a film set to convert a cold daylight source to match other tungsten (warm) light sources.
See also CTB.

1) The command given to technical departments to carry out a particular operation. E.g. Lighting Cue, Fly Cue or Sound Cue. Normally given by stage management, but may be taken directly from the action (i.e. a Visual Cue).
Departments are often abbreviated: Lighting is LX, Sound is SD (or sometimes SX, but this is too similar to LX, so SD should be used). 
2) Any signal (spoken line, action or count) that indicates another action should follow (i.e. the actors' cue to enter is when the Maid says "I hear someone coming! Quick - Hide!" - this is known as a Cue Line
Cues given verbally may be known as 'audible cues', although as this is the normal type of cues, they're usually just called 'Cues'. Cues that technical operators take themselves, without an audible cue, are known as Visual Cues. 
3) A journal published between 1979 and 1988. A complete collection of CUE journals is available on the Backstage Heritage Collection website to read online.
The Prompt Book

System for giving technical staff and actors silent cues by light. Cue lights ensure greater precision when visibility or audibility of actors is limited. Sometimes used for cueing actors onto the set. For technical cues, lights are normally now used just as a backup to cues given over the headset system. In the UK, a flashing Red light means stand-by or warn, green light means go. The actor / technician can acknowledge the standby by pressing a button which makes the light go steady. In the US, a red light means warn, and when the light goes off, it means GO. The UK system seems to be more secure, but it depends what you're used to.

A list of sound, lighting, automation, scene change, video, followspot (etc) cues in order of their appearance in the show. Each cue is given a unique number, and the list includes a brief description of what it does (e.g. for Lighting: Blackout, Dim Downstage Wash, Red Spot Upstage; for Sound: Preshow Music, Fade Out, Snap Music to Quiet etc. )
Cue is often abbreviated to 'Q". 
Also known as a Plot Sheet. 

A philosophy of operation on many computerised lighting desks where the entire lighting state is recorded for each cue.
Some desks which use Tracking only record changes, which means dimmers (or moving lights etc) stay where they are until they're specifically changed. 
See the video below for further information. See also TRACKING. 
Tracking Video
Cue Only Video

Section of a lighting desk which allows a list of pre-plotted lighting states to be 'played back' on the push of a button. These lighting states normally have fade times allocated to them. Lighting desks designed for theatrical use will have this as the primary control, but a rock desk will have more 'hands on' control as a priority, only providing a cue stack for occasional use.

(also known as 'Topping and Tailing')
Cutting out action and dialogue between cues during a technical rehearsal, to save time. (e.g. "OK, can I stop you there - we'll now jump to the end of this scene. We'll pick it up from Simon's line "And from then on it was all downhill" in a moment. OK - we're all set - when you're ready please.")

There is a standard sequence for giving verbal cues:
Stand-by 'Sound Cue 19' (Stand-by first)
'Sound Cue 19 Go' (Go last).

The flow of electricity (electrical charge) through a circuit. Measured in Amperes (Amps)

A list of the coloured lighting gels that are needed for a particular show, including the size of the colour required. There are many different sizes of colour frames for lighting equipment.

A floodlight, usually with an asymmetrical reflector, designed to light a cyc or backcloth from the top or bottom. The asymmetric reflector helps to throw light further down the cloth, producing a more even cover. In the US, a flood at the top of the cyc is a CYC OVER, and a flood at the bottom is a CYC UNDER.
French: Cycliode
Types of lantern


Connecting items of equipment together by linking from one to the next in a chain. Used for connecting demux boxes to dimmers etc.

Lighting design for Dance is reliant on a great deal of sidelight from BOOMS at the side of the stage. There are normally at least three lanterns on each boom, and three heights - SHINS (to light feet and lower legs), MIDS and HEADS.
These booms are sometimes known as BALLET BOOMS. 

As prices are dropping, the use of a data projector connected to a laptop or PC/Mac is within the budget of almost every performance.
See link below for more information. 
Known in parts of Europe as a BEAMER.
See Multimedia Projection for Drama for more information.

DBO (Dead Blackout)


The process of removing lanterns & cabling from flying bars or grid - returning the venue to it's normal state, or as preparation for the next production.
See also STRIKE and GET-OUT.

Boom Arm (Doughty Engineering) A Boom Arm fitted with a scaffold coupler which makes it easy to remove / reposition between shows. 

1) A pre-plotted height for a piece of scenery or lighting bar - 'that bar's on its dead'. The positional indicators on the rope (either PVC tape, or more traditionally cotton tape passed through the strands of the rope) are called DEADS. Sometimes flying pieces are given a number of extra deads, that may be colour coded, in addition to the 'in dead' (lower) and 'out dead' (higher - out of view). In the US, TRIM has the same meaning. Fluorescent ribbon is often used, through the fibres of the rope. The fluorescent colour shows very clearly under UV light, which is often used to light fly floors. 
2) Scenery or equipment not needed for current production - 'that table's dead'.
3) An electric circuit that has been switched off or has failed - 'the circuit's dead, you can change the lamp now'
Submitted by Chris Higgs

A colloquial phrase when the speaker believes that there are a lot of unnecessary cues going on. 
It's the job of the lighting or sound designers to ensure the show can be run reliably every night, in discussion with stage management. If there are lots of cues running in a short period of time, it may be better to simplify them, or make them timed auto-follows, or run them from timecode, to avoid 'death by cues'.

1) Outboard sound equipment that can momentarily stores a signal being sent to part of a P.A. system so that delayed reinforced sound reaches the audience at the same time (or just after) the live sound from the stage. Using the 'Haas Effect' the audience cannot detect the sound as amplified.
2) The term Delay Line refers to the equipment that is used to produce the delayed sound signal.  
3) A function in lighting control software / systems  which holds the start of a cue (or part of a cue) for a specified time. The Delay Time can be used to hold (for example) the Up Time of a cue for a few seconds while the stage is cleared during a dim state. 

Short for De-Multiplex. Interface unit between the serial digital output of a memory lighting control desk to the parallel analogue signal understood by a non-digital dimmer. See MULTIPLEX SIGNAL for more.


1) Lighting: See IRIS.
2) Sound: The part of a microphone which responds to sound waves.
3) Human Biology: (from WIkipedia) a dome-shaped muscular partition separating the thorax from the abdomen in mammals. It plays a major role in breathing, as its contraction increases the volume of the thorax and so inflates the lungs.
4) A rare type of trapdoor. See TRAPs. 

Glass colour filters which reflect all light except that which is the colour of the filter, which passes through.
Normal plastic gels absorb the unwanted colours, turning the light into heat.
Dichroic filters run cooler, and produce a much cooler beam of light. Longer lasting, but a lot more expensive, they are predominantly used in moving lights or architectural applications.
The technology was introduced to the industry in 1988, by Balzers Thin Film Coatings.

A low voltage display lamp with a reflector that lets heat pass through it, rather than reflecting it. Results in a much 'cooler' light.

1) Diffusion is used on film sets to soften the harsh light either from the sun or from high-power film set lighting. It consists of a translucent fire-retardant cloth mounted in a frame, which can be attached to a crane or onto a C Stand. 
2) See FROST.

Many electronic devices use digital logic. Information is handled in separate bits (either ON or OFF) rather than continuously variable analogue signals. Most computer lighting boards give a digital multiplexed output, and more and more sound equipment is going digital.

A more recent generation of stage lighting dimmers that can respond directly to the digital multiplexed output of the lighting desk (ie that don't accept an analogue voltage to provide the channel level).
The technology can also permit the dimmer to report faults and other data back to the control board.

A remotely controllable motorised batten fitted with an integral colour changer. The DLC can now be controlled via DMX (via an interface) although it originally used software called Light Moves running on a Mac. The effect produced by this lantern is a wall of light (when used with a HAZE MACHINE). See also LIGHT CURTAIN.
DHA Lighting website - Digital Light Curtains

Reduction of lighting level for a scene change, that isn't quite a BLACKOUT. Also known as a GREY OUT or BROWN OUT (brown due to the warming orange/brown tones of dimmed tungsten light sources). 

Electrical or electronic device which controls the amount of electricity passed to a lantern, and therefore the intensity of the lamp.
Dimmers in the Backstage Heritage Collection Archive

Area near or on the stage occupied by the dimmer racks and associated power distribution equipment of a touring or festival performance (i.e. a temporary venue). 

ETC Dimmer Doubler A system designed by ETC where two ETC lanterns can be connected to a single ETC dimmer, and have different intensities. It only works with 115V / 60Hz supplies (e.g. USA). A special adapter ('twofer') is connected to the dimmer output. This contains a series of diodes which split the AC sine wave into two halves (positive and negative). Each half is sent to a separate socket on the adaptor and from there to a modified ETC Source Four lantern with a 77 volt lamp. Using these lower voltage lamps means that full intensity is achievable using only half the AC wave. The system will not work in the UK or other countries with 50Hz power supplies as the flickering of the lamps is too noticeable.

The dimmer law in a lighting desk defines the relationship between the control value (fader position) and the console output value (outgoing DMX level).
Submitted by Andre Broucke

The dimmer law defines the relationship between the incoming DMX control value and the dimmer output RMS voltage. Common dimmer laws are 'linear RMS voltage' and 'linear light output'. Around the rated lamp voltage the light output is quite sensitive to voltage variations (a slightly lower voltage can also improve lamp life). If the dimmer is set to 'linear light' and you fade from 100% to 95%, the light output will be reduced by 5%. If you set the dimmer to 'linear RMS voltage' and you fade from 100% to 95%, the light output will be reduced by more than 5%.
Submitted by Andre Broucke


A lighting installation where there is no patching system. Each lighting circuit / socket has a dimmer always connected to it. This has advantages in that you never run out of dimmers, but allows no flexibility and can have cost disadvantages in a large space.

A number of individual lighting dimmer circuits built into a single case. Consists of a single power input, a lighting control (DMX512) input and sockets to connect lanterns. A dimmer rack can be set to respond to any control channel by setting its start address (known as "addressing" the rack).
Also known as a Dimmer Pack (particularly where the number of dimmers in the rack is 6 or less).

Mechanical way of dimming the light output from a discharge lamp or projector when dimming the lamp is not possible. Consists of a series of horizontal blades which are rotated to reduce and then cut the light completely. See also DOWSER/DOUSER.

Deutscher Industrie Normen. European standard covering audio connectors and tape equalisation characteristics.

1) (UK) Also called Dip Traps. Small covered trap at stage level containing electrical outlets. (US equivalent is FLOORPOCKET)
2) Any dimmer outlets at floor level around the stage (e.g. 'What's the nearest dip circuit to downstage left so I can plug the birdie in?')
3) Lighting equipment on stands at stage level. (e.g. 'We're just focussing the dips now')
4) Low lighting intensity when cross fading between two higher states - 'there's a dip between these two states'.
5) Transparent lacquer for colouring lamp bulbs - known as 'Lamp Dip'.

DIP Switches on the rear of an LED Parcan Small plastic switch used to configure the functions of a piece of equipment. Most often used for setting the DMX address of either a moving light, colour scroller, or LED unit. Each switch corresponds either to a binary digit, or to a particular function (ON/OFF).
DIP stands for Dual In-line Package.

Electric current that flows in one direction only (e.g. from a battery). Abbreviated to DC. See also ALTERNATING CURRENT.

A high-powered source of light produced by means of an electrical discharge between two electrodes. An arc light, for example uses a discharge between two carbon rods which are manually or automatically fed together as they are burnt up. The use of this type of lighting is restricted to non-dimming applications such as followspots and projection, where dimming is achieved by mechanical means. Many of the new generation of moving lights use discharge lamps, dichroic filters and mechanical dimming shutters.

(US) Also known as a COMPANY SWITCH, this is a large capacity power connection point on/near the stage which touring companies can use to connect their equipment.

Interface connected between two or more slide projectors and a tape player. Synchronisation signals recorded onto the tape are detected by the dissolve unit and fade up the lamp in one slide projector while changing the slide in the other, and then vice versa, producing a dipless crossfade between the two images.

System of interconnected fuses / circuit breakers and cabling that routes an incoming power supply to a number of different outputs. Known colloquially as DISTRO or the DIS BOARD.


Powered device which is used to boost a DMX512 signal so that it can reliably travel over a long distance.
The maximum distance for a DMX512 signal is 300m - using a buffer you can send the signal an additional 300m.

Lighting control accessory which accepts multiple DMX inputs (e.g. from a number of lighting controllers) and merges them together to a single DMX feed to control dimmers or moving lights etc.

A DMX terminator is a 3 or 5 pin XLR connector which is used at the end of a DMX run to absorb the data signal to stop it being reflected back along the DMX cable. The terminator is very easy to make, and consists of a 120 Ohm half-watt resistor soldered between pins 2 and 3 of the XLR connector. A DMX run should always be terminated, and although the system may work without one, continued operation cannot be guaranteed. A system with poor quality DMX cable (or cable of a long run) will require termination in order to operate correctly.

Short for Digital Multiplex. See MULTIPLEXED (MUX) SIGNAL.


1) (Aus) Follow spot location usually at rear of the upper gallery. Sometimes referred to as BIOBOX, where the control booth and followspot position are the same.
2) (Aus) A Followspot in any location (from the above).

Australian term for the followspot operator. See DOME.
Submitted by Mac Calder

A metal plate with a hole in the middle inserted in the colour runners of a lantern to sharpen focus (in the case of a profile) or reduce spill.

An object or tool that you're not sure of the correct name for. For example, 'Pass me the doofer so I can sort this thingy'.

To rig two lanterns adjacent to each other in different colours, both covering the same area. 


A light from directly above the acting area. A downlight could be a spot or a wash of light.

End-On Stage Layout Plan ( 1) The part of the stage nearest to the audience. It's called Downstage because it's the lowest part of a raked stage. Downstage Left (DSL), Downstage Centre (DSC) and Downstage Right (DSR) are commonly used for the areas towards the front of the stage. [See Diagram]
2) A movement towards the audience (in a proscenium theatre).

A metal flag used in larger followspots and projection equipment to cut off the light beam without cutting off the electrical supply. Discharge lamps cannot be dimmed, so this is the only way of stopping light. Discharge lamps need a period of cooling down when they are turned off before they can be turned on again, so they should not be switched off if needed again within about two hours.

A brief pause (a few beats) in an actors' delivery of a line to emphasise a moment or to heighten anticipation. 
It's important that the DSM does not shout out the next line, while the lead actor is pausing dramatically. 

Providing a low level of lights to an open stage while the audience enter the house up until the performance starts. Also known as PRESET.

A full rehearsal, with all technical and creative elements brought together. The performance as it will be 'on the night'.
German: hauptprobe (final rehearsal)

A length of suspension wire of standard length with eyelets at each end between the counterweight bar and the top of the scenic piece flown from it.

Frozen solid carbon dioxide (CO2) at a temperature of -78.5° centigrade which produces clouds of steam-loaded CO2 gas forming a low-lying mist or fog when dropped into boiling water. Although non-toxic, caution is required in the storage and handling of dry ice because of its extreme cold. Water is boiled in a large tank offstage, into which the dry ice is lowered in a basket. Fans and ducts then direct the gas onto the stage. Dry ice does not support life, so care should be taken that small animals, actors etc.are not below the level of the dry ice for more than a few seconds.
See also LOW SMOKE.
Fog / Smoke / Haze On Stage

The member of the lighting team on duty for a particular event. Also known as DUTY LX. 

File type for a CAD file (short for DraWinG). The format is used for storing two and three dimensional design data and metadata. It is the native format for several CAD packages including AutoCAD, IntelliCAD (and its variants) and Caddie. In addition, DWG is supported non-natively by many other CAD applications. The .bak (drawing backup), .dws (drawing standards), .dwt (drawing template) and .sv$ (temporary automatic save) files are also DWG files.

(ERS) Ellipsoidal Reflector Spotlight (US)

Copper rod inserted into the ground to maintain earth continuity (especially when using generators etc.)

Electrical safety requirement that metal parts of electrical equipment are connected to a common earth or ground point so that in the event of a fault, excess current can be carried away, causing the fuse to blow. Known in the USA as Ground. Some sound problems (such as hums) can be cured by altering the earthing / grounding arrangements of the system, but this should never involve removing the earth connections to equipment, only by adding an earth connection where none exists, or by adjusting the way audio cables are wired. Seek professional advice to avoid safety problems.

Heavy duty power connector in the USA - a circular plastic body with three metal contacts.
See also GPC, NEMA. 

Circular threaded lamp holder which is one of the standard fittings for domestic light bulbs. Other common types are BC (Bayonet Cap) and SES (Small Edison Screw). GES (Giant Edison Screw) is used for large wattage lamps.
The measurements below are the diameter of the lamp base (at the crest of the thread). 

Miniature Edison Screw (MES) is 10mm (E10)
Mini Candleabra Edison Screw (Mini-Can) is 11mm (E11)
Candleabra Edison Screw (CES) is 12mm (E12)
Small Edison Screw (SES) is 14mm (E14)
Edison Screw (ES) is 27mm (E27)
Mogul base is 39mm (E39)
Giant Edison Screw (GES) is 40mm (E40)

Acronym for Electronic Dance Music. Repetitive beats and an awesome light show.

VSFX3 Effects Disc and Effects Projector (City Theatrical) Lantern used to project the image from a rotating glass effects disc. Used with an objective lens to produce the desired size of image. Commonly used discs are clouds, flames and rain.
See also: Lighting Effects

Physical Effects:
Animation Disc
: A slotted or perforated metal disc which rotates in front of a lantern to provide 'movement' in the light. Most effective when used in front of a profile carrying a gobo.
Effect Disc: A painted glass disc rotating in front of an effects projector with an objective lens to focus the image (eg Flames, Rain, Snow).
Flicker Flame: Irregularly slotted rotating metal disc through which light is shone onto a prism-type piece of glass which scatters the beam of light and adds the 'dancing' effect of firelight to a scene.
Gobo Rotator: Motorised device inserted into the gate of a profile lantern that can be remotely controlled to rotate a gobo, usually with variable speed and direction.
KK Wheel: Slotted metal disc which rotates in front of a lantern to break up the light and provide movement. (Flicker Wheel)
Lightning: Created through the use of strobe sources or LED floods. Photoflood lamps were used in the past, but have a very short life, and aren't as bright as the other options.
Tubular Wave Ripple: Horizontal linear lamp around which a slotted cylinder is rotated providing a rising light (as reflected from water onto the side of a ship).
Programmed Effects:
Most modern lighting desks (and some very old ones) have the ability to add 'movement' to lighting states by changing the lighting states in various ways. These effects can be set up to run at the press of a button, or can start or stop when a particular cue is run. 
Chase: A number of different 'steps' are added which are then repeated until the chase is stopped. 
Flicker: Particular channels are set to randomly move between levels, with adjustable timings and other parameters.
See also: Pyrotechnics
Lighting Effects
Fog, Smoke & Haze On Stage

Slang term used for Strand Pattern 123's, due to their shape.
Strand Archive

Electro-luminescent Wire. Requires an alternating current power supply of between 90-120 volts, but this is usually generated by an oscillator circuit powered by a few AA batteries. The wire is very efficient and robust. The weak points tend to be the connections between the wire and the power supply, so ensure these are well-protected if the wire is being used in/on a prop or costume.

In the US, LX bars are ELECTRICs bars.
LX1 in the UK (first bar upstage of the proscenium arch) is FIRST ELECTRIC in the US.
In the UK, the bars front-of-house (audience side of the proscenium arch) are usually given names (e.g. Advance Bar, Front Perch, Circle Front) and upstage of the proscenium are numbered, with LX1 as the most downstage.

See LX.

The Electromagnetic Spectrum (from The electromagnetic spectrum is a way of describing all of the types of electromagnetic radiation in order of wavelength. The spectrum includes visible light (which are of most relevance to theatre), radio waves and other types of radiation.
For light, the spectrum starts with infra-red radiation (which we feel as heat), then the visible light colours run from red (around 700 nanometers), through orange, yellow, green, blue to violet, and then ultra-violet radiation. 
Encyclopaedia Britannica entry
Wikipedia entry

A working drawing usually drawn to scale, showing the side view of a set or lighting rig. See PLAN.
In the US, the term "elevation" refers to a Front elevation. A Rear elevation shows backs of scenic elements. A side view of a set is known as a "section".

Strand Lekolite 8 x 13 A profile lantern with an elliptical reflector and at least one lens. Also known as an ERS (Ellipsoidal Reflector Spotlight).
A common type was the LEKO, made by Strand, but this has been eclipsed by the Source Four range, made by ETC.

A self-contained lighting system for a public space that provides enough illumination for the public to leave the area and to locate exits in the event of a power cut.
Emergency Lighting systems should be checked regularly (as required by local licencing authorities).
It's especially important to consider power cuts when using non-theatre spaces (especially outdoor spaces) for performances.

Abbreviation for Electromotive Force, or VOLTAGE.

A flat disc with an indentation used to control certain functions of (often) moving lights on a lighting control desk.

End-On Stage Layout Plan ( Traditional audience seating layout where the audience is looking at the stage from the same direction. This seating layout is that of a Proscenium Arch theatre.
Also known as Proscenium Staging.
The end-on stage can be split into 9 areas: upstage right, upstage centre, upstage left, centre stage right, centre stage, centre stage left, downstage right, downstage centre, downstage left.

Any technical or practical craft used in the creation of live events or experiences. As the definition of 'live events or experiences' includes music concerts, theatre, theme parks, visitor attractions, museums and sports events, the skills needed are very broad. It's not necessary for anyone to be highly skilled in all of the crafts, but an understanding of the whole picture is very helpful, and knowing when to call in a specialist (and where to find them) is vital.

The crafts involved in entertainment technology include, but are not limited to:
Lighting (stage lighting and architectural lighting)
Sound (live and recorded)
Video and Media (projection or display)
Scenic Construction and Automation
Show Control
Props and Masks
Make-Up and Prosthetics

ETC lighting control software, used on a wide range of lighting systems they've designed, including the Eos desk, the Ion, Gio. 
The software had a major upgrade with version 3.0 in 2020, when the Augment3d functionality was added, enabling visualisation and a host of other features, all within the lighting control software. 
The Eos software can run on Windows or Mac PCs as well as the lighting desks, and can control lighting rigs with the addition of a Nomad dongle (to authorise) and a Gadget device to output DMX512, or via an ethernet cable to control ArtNet or s-ACN systems. 

More on Ghost Light

ER / E.R.
(US) Short for Ellipsoidal Reflector - type of fixed beam profile lantern common in the US. Also known as ERS / E.R.S. See also LEKO.

ERF / E.R.F.
(US) Short for Ellipsoidal Reflector Floodlight. See also ERS.

ERS / E.R.S.
(US) Short for Ellipsoidal Reflector Spot. See PROFILE for more. See ER, also ERF.

(US) Entertainment Services and Technology Association. See PLASA for the UK equivalent.
ESTA website

(Manufacturer) US/UK based manufacturer of lanterns and lighting control equipment.
ETC website

Computer networking protocol which is installed on many new lighting desks, to allow networking between the main desk, dimmers, and remote desks around the theatre.

Usually illuminated sign, of standard size, which should always be visible, showing an audience member and the company the nearest exit.New legislation in Europe means that the word 'EXIT' has been removed from these signs to be replaced by 'Running Man', known more politically correctly as 'Person moving purposefully'.

Theatre design and performance style which places greater value on emotion than realism. The trademark Expressionist effects were often achieved through distortion.

A cable used to connect equipment to a power socket which is too far to connect directly. 
Extension cables are available either with a single outlet or multiple outlets. 

Lighting equipment used (especially at live music events) to look good to the audience or the camera, rather than being used to light the performers. This is distinct from equipment used to light the air above / around the band (when haze or smoke is in use) as this has a scenographic function. Eye Candy equipment provides limited functional light. 

Abbreviation for Fade to Blackout.

A fade is an increase, diminishment or change in lighting or sound level.
A snap fade is an instant change. A slow fade could be anything from 5 seconds to a few minutes (or even more, for a naturalistic sunset lighting effect). A quick fade is a couple of seconds long.
A fade out takes the lighting state to blackout (or a particular sound to silence). A fade in does the opposite.
A crossfade smoothly transitions from one state to another, without going through darkness (or silence for sound).

A slow dimming of the lights to a lower level, but not all the way to blackout. See also FADE OUT.

A slow dimming of the lights, ending in blackout. See also FADE DOWN.

On computerised memory lighting control desks, a lighting fade can have two times - an up fade and a down fade.
The Up fade time refers to the time it takes dimmer levels to rise to their new positions.
The Down fade time refers to the time for dimmer levels falling to their new positions.
In a CrossFade, the fade times are the same for both elements of the fade (up and down). In a Split Fade, the times are different. 
See also DELAY, FOLLOW. 

An increase in lighting or sound level, over a given time period. An increase in level from an existing state is known as a BUILD.

A vertical slider which is used to remotely set the level of a lighting or sound channel.

ETC EOS Motorised Fader Wing (10 way) A separate accessory added to a lighting desk or to a computer running lighting software, which gives you a bank of faders, which can control either individual channels, or act as submasters (storing lighting states or effects), or act as cue stacks, effectively giving you a number of playbacks. 

(US) Lighting instrument used to light cycloramas or drops (see also CYC FLOOD).

A common problem among lighting & sound operators, when two buttons are accidentally pressed at the same time by a finger that's too large for the buttons. 

A combined fogger and hazer, which can produce thick or thin smoke / haze.

1) A power supply to a piece of equipment or installation is termed a 'feed'. Sound equipment and sensitive computer equipment should have a clean feed - that is, a supply that is free from interference from other equipment.
2) A signal from one system to another is also known as a feed (for example, an audio signal from the FOH desk to a TV company videoing a concert is known as a feed. A video relay of the conductor to screens in the wings is known as a Conductor Feed, etc.)

In the US, a main power cable to an installation is known as a feeder.

Osram FEL 120V lamp ANSI standard 1000W lamp, with a G9.5 medium 2 pin base, and is made by a number of manufacturers including GE, Osram, Ushio, Eiko and Philips.

This terminology is beginning to change, as it's not very subtle, and sometimes isn't as clear as it could be. 
Connector manufacturers and crew members refer to plug connectors (with pins) as MALE, and sockets (which receive the pins) as FEMALE. 
Many modern companies refer to plug and socket instead of the genderised terms, but that in itself can cause confusion. The situation remains confusing. 
Sound: Microphones have pins on them, so a XLR cable socket is used to connect to them. The other end of that cable is a plug, which connects to the mixing desk. 
Power: Sockets are used to supply power so that it's not possible to touch live connectors. Plugs are used to connect equipment to the supply. 

1) See Swag
2) Describes tabs which adopt a sculpted shape.
3) A length of cable incorporating a number of lamp holders used for outdoor party lighting etc. Available in multi-circuit form so that the lamps can be 'chased'.

A colour frame made from heat resistant fibres, which doesn't get as hot to the touch as a standard metal frame.

A method of directing light down a very thin glass fibre. Fibre Optics are used mostly in communication, but find theatre applications in star cloths which are black backcloths with the ends of optical fibres poked through, to create a mass of pin pricks of light. A large bundle or harness of fibres may be fed from one light source, sometimes with a motorised colour or flicker wheel.
New technology enables digital sound signals to be sent down optical fibres, replacing heavy and expensive multicore cables.

Refers to the spread of light intensity across a beam. Most profile lanterns have an adjustable field. A Flat field has an even distribution, a peak field has a 'hot spot' in the centre of the beam. A flat field is essential when using gobos.
The Field Angle is a measurement of the width of the cone of light produced by the lantern until the light falls off to 10% intensity. This is a wider angle then the Beam Angle, which is a measurement of the cone of light until the light falls off to 50% of full intensity.
For a sharply focussed profile, the Field angle and the Beam angle will be very similar (or identical). For a Fresnel or Parcan, there will be a difference between the two. It's best to use Beam Angle when calculating lantern coverage.

Narrow PAR64 lamp (240V) and the beam it produces which is a projection of the filament of the lamp. Metal which heats up and glows white hot when electric current runs through it. Dimmable stage lights traditionally use tungsten filaments in a halogen gas (known as Tungsten Halogen lamps). As most of the electrical energy is wasted as heat, more efficient ways of creating light (e.g. LED) are now more in favour. 
The light produced by a parcan is effectively a projection of the shape of the filament (known as the Filament Image). This is especially evident with the CP60 (narrow) PAR64 lamp, which has no frosted glass or lens to soften the image. 

(especially TV and Film lighting) Light which fills the shadows that key light creates.

1) See Colour. 2) Electronic device to isolate and redirect specific frequencies in a speaker system.

Important skill for an actor - being able to feel the light on your face, to know when you are correctly standing in a spotlight or lit area, and when you are standing just out of it. 

Essential tools of the pyrotechnician's trade ! In the UK, they used to be colour-coded according to content (Carbon Dioxide (Black), Water (Red), Foam (Cream), Halon Gas (Green) Powder (Blue)) but now, they're all red with a small label saying what they are. Another great leap forward !.

(US) The first LX bar upstage of the proscenium arch. (Known in the UK as LX1). The next bar is known as Second Electric, and so on. 

Doughty Engineering T30100 - Pipe to Pipe Coupler (Fish Plate - 48mm) Colloquial name for a coupler to join two pieces of pipe (e.g. 48mm scaffolding tube) together. 

Initial assembly on stage of a production's hardware, including hanging scenery, building trucks etc.
See also GET-IN

A single moving light unit. Used instead of "instrument", "lantern" or "luminaire" due to the added complexity of the equipment and the need for additional control connections.

When focussing lighting, flagging means waving your hand in and out of the beam of a lantern/instrument in order to see where the beam is hitting on stage. Flagging is particularly useful in high ambient light levels. (e.g. 'Can you flag that please ?') Term probably originates from a FRENCH FLAG.

Flash Pods for use with the Pyroflash system (Le Maitre) A small box containing the socket into which a pyro cartridge is plugged. Also known as a flash pod or firing pod.
German: Startbox

A push switch on a lighting desk which flashes selected channels / memories / submasters to full (100%) while pressed. Some Flash buttons on submasters can be set to latch (ie they stay on when pushed, until they are pushed again).
Sometimes known as a Bump Button.


Method of checking whether lanterns are functioning properly by flashing them on one at a time. It is good practice to flash lanterns to 70%, rather than Full to preserve lamp life.

Flash paper is fast-burning nitrocellulose (Cellulose Nitrate) which is used by stage magicians to produce a flash of flame safely. The paper (or cotton) made from nitrocellulose burns almost instantly leaving no ash or residue.
Flash Cotton is cotton wool / string impregnated with nitrocellulose. It should be stored wet, and allowed to dry out just before use.
Wikipedia entry

The flying system above the stage of the theatre, consisting of the FLY TOWER, FLY FLOORS, COUNTERWEIGHT systems, PULLEYs, LINES etc. 

Metal framed wooden box on wheels with a removable lid used for transporting equipment between venues. Flightcases are very strong, and have reinforced corners and edges. Care should be taken when lifting flightcases as they can be very heavy.
The term comes from their original use in protecting delicate equipment when being loaded into air transport and being both very strong and relatively lightweight.
Additional information by Chris Higgs

Early form of footlights using burning wicks floating in oil across the front of the stage. Now applies to anything rigged on the front edge of the stage (eg Float microphones, Uplights / footlights etc.)

Coda 500W Flood 1) A lensless lantern that produces a broad non-variable spread of light. Floods are used in battens, or singly to light cycloramas or large areas of the stage.
See also CYC FLOOD.
2) To increase the beam angle of a Fresnel or PC by moving the lamp and reflector towards the lens. 'Flood that a bit, please!'. The opposite movement is called Spotting.
Types of lantern

Lanterns mounted on low stands at stage level so they provide uplight, casting shadows across the stage.
Rigging Positions

(Gigs) The lighting equipment brought by a touring band / production which sits on the stage deck on ground-supported truss, lighting stands or other frames. The floor package is used alongside the venue rig. 

A low mount for a lantern so that it can sit at stage level. 
A floor stand consisting of a sheet of metal and a central support is known as a FLOOR PLATE. 
Stage Rigging Positions

A PARCAN with an extra trunnion arm / yoke, and often a short nose, which is designed to sit on the floor.

(US) A electrical socket mounted under a flap in the stage floor (UK equivalent is DIP).

(Colloquial) UK term for the fluorescent working lights over a stage / in a venue. (e.g. 'Please get the florries off in the corridor because we can see them through the upstage door').

A way of describing the movement of the lighting on stage from one state (or scene) to another. This flow can help keep the pace of the production moving forward, without the end of the scene leading to an unnatural pause. 

The property of some materials to glow when subjected to light. This normally refers to ultraviolet light, although blue visible light (along with many other colours) can cause fluorescence. The materials degrade the UV wavelengths into longer and therefore visible reflected rays. See also Phosphorescence.

The metal bars to which scenery and lanterns are attached for flying above the stage. 

(Manufacturer) Makers of the Wholehog / Hog range of lighting control desks.
Flying Pig Systems website

The focal length (property of a lens) is the point at which parallel rays from the sun will converge on passing through the lens. It follows that if a light source is placed at the focal point, the lens will produce parallel rays. If a light source is placed between the lens and the focal point, diverging beams will result. If a light source is placed beyond the focal point away from the lens, converging beams will result.

1) The session when all the lanterns / instruments in the rig are angled in the correct direction, with the correct beam size.
2) Description of how sharply defined a light beam is ('give that profile a sharp focus')
3) Control on projection equipment used to change the focus.
Lighting Focussing at

Documentation produced by the lighting designer which shows graphically the exact focus of a particular lantern in the rig. Essential for long-running shows where the crew can use it as a reference when replacing lanterns or checking focus after cleaning etc. The charts can also be used to do a 'rough' focus before a lighting designer arrives at the venue. Touring shows sometimes use a floorcloth marked out with focus information to aid speedy focussing in a new venue.

Function on some computerised lighting desks which allows the operator to specify a place on the stage to which moving lights can be made to move on cue. Once defined, the focus point can easily be recalled and used in multiple cues. If the location of that item is moved (e.g. the chair is moved to the right) all moving lights will automatically focus on the new location.

Term for both Fresnel and PC type lanterns with adjustable beam size.
Types of lantern

The process of adjusting the direction and beam size of lanterns. Does not necessarily result in a 'sharply focused' image.




A cue that happens so soon after a previous cue, that it doesn't need to be cued separately.
The follow-on can be taken by the operator once a previous cue is complete, or a lighting or sound cue can be programmed to happen a specific time after a previous cue.
Fly follow-on cues are often taken as soon as the operator has completed a previous cue. Often abbreviated to F/O.

Usually, a powerful profile lantern usually fitted with its own dimmer, iris, colour magazine and shutters mounted in or above the auditorium, used with an operator so that the light beam can be moved around the stage to follow an actor. Sometimes a beam light or other lantern may be used in the same way.
Powerful followspots use discharge lamps which cannot be dimmed, so these followspots have mechanical dimming shutters to dim the light output.
The Followspot control position is sometimes a separate room soundproofed behind glass, and sometimes in a high position within the auditorium, depending on the theatre. 
Followspotting Tips and Tricks
Followspots on the Backstage Heritage Collection archive

1) The action of bracing the bottom of a ladder while a colleague climbs it (e.g. 'Can you foot this for me please? I'll only be a couple of minutes').
2) Holding the bottom edge of a flat with your foot while a colleague raises the top of it to a vertical position (known as 'footing a flat').

Marking on lighting bar each foot (12 inches) to make rigging more accurate. The centre line (C/L) is marked on the bar, then each foot outwards from centre to stage left and stage right is marked (and sometimes numbered for ease).

An non-SI unit of illuminance (or light) used in film, TV and architectural lighting industries. The unit is defined as the amount of illumination the inside surface of a 1-foot radius sphere would be receiving if there were a uniform point source of one candela in the exact center of the sphere. Alternatively, it can be defined as the illuminance on a 1-square foot surface of which there is a uniformly distributed flux of one lumen. This can be thought of as the amount of light that actually falls on a given surface. The foot-candle is equal to one lumen per square foot.
The SI derived unit of illuminance is the lux. One footcandle is equal to approximately 10.764 lux, although in the lighting industry, typically this is approximated as 1 footcandle being equal to 10 lux.
In the lighting industry, footcandles are a common unit of measurement used to calculate adequate lighting levels of workspaces in buildings or outdoor spaces. Footcandles are also commonly used in the museum and gallery fields, where lighting levels must be carefully controlled to conserve light-sensitive objects such as prints, photographs, and paintings, the colors of which fade when exposed to bright light for a lengthy period.

A compartmentalised flood batten sometimes recessed into the front edge of the stage, used to neutralise shadows cast by overhead lighting. Before battens were used, individual light bulbs with ornate shades to shield the glare from the audience were used. Modern lighting equipment renders footlights virtually obsolete except for period/special effects. See also FLOATS. 

Fouling occurs when a piece of flown scenery / drapery gets caught on a piece of scenery on the stage floor, or another piece of scenery / lighting bar etc in the rig. Fouling sometimes happens due to changes in temperature / air pressure causing lightweight scenery or curtains to move in a particular direction. Happens frequently in tightly-packed flying systems. 
Sometimes lighting designers need to remove additional equipment (e.g. barndoors, top hats) from lanterns in the rig because other scenery or curtains get caught on them. 

Built into some moving lights, these motorised shutters allow the beam to be cut off or to form a flat-sided shape, under control of the lighting desk. 
They're specifically named Framing Shutters to differentiate them from Dimming Shutters, which are used on moving lights with discharge light sources (which can't be put on a dimmer), and are used to dim the light by mechanically cutting off the beam. 
The framing shutters are positioned in the same position as a gobo, so a sharp focus can be obtained. 
As well as being brought in or out of the beam, each of the 4 shutters can be angled, so a range of shapes can be formed. 

Film/Video term. A card or metal panel fitted to an adjustable arm used to stop unwanted light from directly entering the lens of a camera.

Selecon Acclaim Fresnel (500W) (pronounced "Fre-nell")
A type of lantern which produces an even, soft-edged beam of light through a Fresnel lens. The lens is a series of stepped concentric circles on the front and pebbled on the back and is named after its French inventor, Augustin Jean Fresnel (1788-1827). He developed the lens for French lighthouses so that they could be seen further out to sea and could achieve a longer focal length with a lot less glass than a standard plano-convex lens.
Fresnels usually have a focus knob which is used to make the beam larger (flood) or smaller (spot), by moving the lamp and reflector closer to or further from the lens. they also have a set of barndoors on the front of the lantern whih are used to cut off unwanted parts of the beam by casting a shadow.
Sometimes shortened to just 'F' (e.g. 'Can you tighten the focus on the downstage Fs so there's less spill on the front of the stage').
Types of lantern

1) Every part of the theatre in front of the proscenium arch. Includes foyer areas open to the general public.
2) All lanterns which are on the audience side of the proscenium and are focussed towards the stage.
The backstage areas of the theatre are known as Rear of House (ROH).

A diffusing filter used to soften the edges of a light beam. Frosts are commonly used in profiles in front of house positions to achieve the same beam edge quality in all lanterns. Different strengths of diffusion frost are available from many colour filter manufacturers.
Rosco make a range called Hamburg Frost - see link below.
See also SILK.
Rosco Hamburg Frost range

Initialism of Fade to Black - a gradual reduction in lighting levels towards blackout.
Originally a shorthand in TV/film scriptwriting, where it refers to a fadeout in camera rather than a lighting effect.  

2) File Transfer Protocol - a method of transferring files across the internet.

A bright lighting state with general cover lanterns at 'full' (100%) intensity. See also FULL UP FINISH.

A shorthand note for manual desk lighting operators to bring all relevant dimmers to full for the end of a song / finale of a show to 'draw the applause'. Still applies for the snap build on the last beat of a song. See also LIGHTS UP, FULL UP. 

Fuse - 1A Glass Cartridge Fuse 5 x 20mm (from RS Components, UK) Protective device for electrical equipment (E.g. dimmers). Every piece of electrical equipment has at least one fuse in its associated circuit. The thin wire inside each fuse is designed as the 'weak link' in the circuit so that once the rated current is exceeded, the wire literally melts, breaking the circuit, and preventing further damage to the rest of the equipment. 

A lamp with a revolving mirror and a coloured plastic dome. Gives a 'police light' effect. Usually 12 Volt or 240 Volt operation.

Ubiquitous sticky cloth tape. Most common widths are .5 inch for marking out areas and 2 inch (usually black) for everything else. Used for temporarily securing almost anything. Should not be used on coiled cables or equipment. Originally known as Gaffer's Tape, from the Gaffer (Master Electrician) on a film set. Also known as Duct Tape.
See also PVC Tape.

(Trade Name) Large computerised memory lighting desk. Previously manufactured by Rank Strand (now Strand Lighting)
Strand Lighting website
Strand Archive

(Manufacturer) USA based manufacturer of lighting gels, gobos and accessories. GAM stands for Great American Market. See COLOUR FILTER, GOBO.
GAM website

Distribution point for gas used in theatre lighting (from around 1816 - 1890). Various valves and wheels controlled the flow of gas from the central point to each part of the stage, so that by using a team of people, complex lighting fades could be achieved, before the advent of electricity for lighting. According to Richard Pilbrow (Stage Lighting Design: The Art, The Craft, The Life 1997) the gas table was the first stage lighting switchboard.

1) The point of focus in a profile spot where the shutters are positioned and where an iris or gobo can be inserted.
2) A single base section of a folding rostrum system.

Cloth with a relatively coarse weave. Used unpainted to diffuse a scene played behind it. When painted, a gauze is opaque when lit obliquely from the front and becomes transparent when the scene behind it is lit . Many different types of gauze are available;
Sharkstooth gauze is the most effective for transformations, because it is the most opaque.
Vision gauze is used for diffusing a scene and for supporting cut cloths.
HoloGauze™ is a metallised gauze optimised for front projection holographic illusions.
Also known as a Scrim, American Mesh.
Gobelin Fabric is used for tapestry making and has a less coarse weave than theatrical gauze, but will work for smaller shows. 
Voile / Net curtain material will work well and takes projection very well (as the thread is much finer than cotton gauze). 
See also Lighting With A Gauze / Scrim

General Device Type Format. An open-source format for fixture manufacturers to supply fixture profiles to lighting console manufacturers. 
GDTF website


(Trade Name) Medium size computerised memory lighting desk with 180 channels. Previously manufactured by Rank Strand (now Strand Lighting)
Strand Lighting website
Gemini in the Backstage Heritage Collection

Those lanterns in a rig which are set aside purely to light the acting areas.
The stage is normally split into a number of areas for this purpose, which can then be isolated or blended together as required by the director. 
See Special.
Designing and Focussing a General Cover

Fuel-powered engine which drives a dynamo to convert mechanical energy into electricity. Also known as a GENNY. 
Generators are used as back-up power supplies in the event of failure of the mains electricity, or to supplement the power available in a venue for a specific show that requires a large amount of electrical power.
Also used on outdoor events to provide all power (including sound system, lighting rig, catering, emergency lighting etc). A large event will have a number of generators and back-up generators to power different zones of the site. 

Standard stage lighting instruments, rather than moving lights or other effects. (e.g. 'There are 40 instruments in the rig - 20 moving lights and 20 generics'). 

(Trade Name) A range of mobile access platforms or lifting devices with either hand-cranked or compressed air lifting mechanisms.
Genie Industries website
Access Equipment


Moving an entire production out of the venue, and back into storage or into transport. Usually preceded by the strike (where the set is disassembled back into component parts.
The Get Out is also known as Load Out (USA) or Bump Out (AUS.) or Pack Out (NZ).

GFI / G.F.I.
(US) Ground Fault Interruptor. See RCD.

Ghost Light (ramagrrl on Flickr) (US) A light left burning overnight on stage to keep friendly spirits illuminated and unfriendly spirits at bay. Also believed to keep the theatrical muse in a 'dark' theatre, and to stop people tripping over bits of scenery when they come into the theatre in the morning.
The ghost light consists of a vertical pole with a bare light bulb on it, and is placed on stage. Care should be taken that the cable doesn't create a trip hazard, and that the light bulb is protected with a metal cage. 
The type of bulb is not critical - it should be chosen so that enough light is emitted to enable people on stage to see furniture / other items to stop them tripping over. Where possible an energy-saving lamp should be used. 
Also known as the 'Equity Light'. See link below for more information.
Could also refers to the light emitted by a lantern when a dimmer has not been 'trimmed' correctly, and is leaking.
French: La servante
More information about Ghost Light

A lamp plugged into a dimmer which is also being used to dim an inductive load (e.g. transformers) rather than a resistive load (filament lamps). Most dimmers (and certainly all cheap dimmers) are designed for resistive loads, so adding a load lamp onto each dimmer circuit that's not being used for resistive loads enables the dimmer electronics to work correctly.
A ghost load is also used to increase the load on a dimmer when using very low wattage equipment. The ghost load is positioned next to the dimmers out of view of the audience and connected via a parallel splitter (e.g Grelco). 
Also known as a LOAD LAMP.

A method of determining the exact position of a followspot's beam by faintly exposing it on a darker area of the stage or upon the drapes. Often done just before a 'pick up' so the operator can have the lantern aimed and ready. A more professional practice is to use sights to line up a followspot.
Submitted by Jayson Bowles

Blue backlight & glass Moon gobo - Northcott Theatre Exeter - Far from the Madding Crowd (lighting by Jon Primrose) A highly detailed gobo consisting of an aluminium pattern sandwiched between two thin pieces of glass. A glass gobo is more expensive than a standard steel gobo, and requires special handling. A glass gobo holder must be used which allows the glass to expand when heated. When used in lanterns more powerful than around 650W, the lamp should be preheated before being turned to full to warm up the gobo, otherwise the thermal shock may cause the glass to crack.

1) (especially TV and Film) Jargon for a replacement lamp.
2) The glass part of a lamp.
3) The Globe Theatre in London.
See also BUBBLE, LAMP.

Used when lifting heavier lanterns or other equipment.

General Lighting Service. Lamps designed for general everyday use.

1) A button on a lighting or automation control console that executes a cue. The button is usually labelled GO. 
2) (Trade Name) A remote control for a computer running QLab software. 

Gobos through Haze (Oliver at the Northcott Theatre, UK; Lighting Design by Jon Primrose, Set & costume design by Becky Hawkins) ( A thin metal plate etched to produce a design which can then be projected by a profile spotlight. There are hundreds of gobo designs available - common examples are breakup (foliage), windows and scenic (neon signs, city scapes etc.). The image can be used soft focus to add texture, rather than a defined image. A number of composite gobos in different coloured lanterns can, with careful focusing, produce a coloured image (e.g. a stained glass window). Greater detail can be achieved using a glass gobo, which consists of a thin layer of aluminium etched onto glass.

Origin of the term 'gobo'
There are a few possible origins for the word GOBO but nothing definitive yet.
Although it's tempting to believe it's an acronym or abbreviation for 'Graphical Optical BlackOut' or 'Goes Before Objective lens' this is not true, as the term is also used in connection with sound recording (a microphone gobo blocks sound from adjacent sources) and also in the film industry, where it's a piece of equipment to block light from the lens or an area. .
It could be short for Go-Between, as the gobo goes between the lamp and the lens.
Material from 1967 uses the word 'MASK', and no mention is made of 'GOBO', so we can assume the word wasn't in widespread use then for stage lighting. In the US TV/Film industry, a Gobo is a piece of material used to mask or block light, placed in front of a lantern (also known as a SHADOW MASK) and a Cookie (short for Cucaloris(from the Greek kukaloris: the breaking up of light)) is the same as a UK Gobo. PATTERN and TEMPLATE can also refer to a gobo in some areas.
In the film industry, the word gobo can be used as a verb (e.g. 'We need to gobo off that light so the camera doesn't see it').
Gobos are available in a wide range of sizes, for use in different profile lanterns and other projectors (e.g. moving lights). 
A size - 100mm outside diameter / 75mm image diameter
B size - 86mm / 64.5mm
D size - 53mm outside diameter
M size - 66mm / 48mm
E size - 37.5mm / 28mm
Moving lights use a range of different gobo sizes, so check the manufacturers website. 
Lighting Effects

Gobo Holder (B size) A metal plate designed to hold a gobo of a particular size in a lantern of a particular type. 
Different size gobos need different gobo holders, and different lanterns have specific size gates, into which the gobo holder is inserted.
Glass gobos require a special type of gobo holder, which holds the gobo securely, but also allows it to expand with heat. 
The gate is between the lamp and the lenses, at the midpoint of the lantern, and is part of a profile lantern. A gobo can't be used in a fresnel or flood.


A bright intense beam of light from above to isolate a performer on stage, as if from God. 
Previously achieved with a parcan, but now often a moving light. 

Warning to people on stage that the lights are about to be switched off. Normally said during lighting plotting sessions or technical rehearsals. Obviously should not be done if there is any risky work on stage, or if anyone is up a ladder / using power tools / working on platforms / rehearsing choreography etc.

Warning that a flying bar is about to be lifted. 
e.g. "LX3 Going Out".

Altman Male Stage Pin Inline Connector - 20 Amps (from BH Photo website) (US only) Grounded Pin Connector. A 3 pin plug used to connect instruments to cables / lighting circuits.  Also known as Stage Pin Connector. 


Graphite Lubricant (RS Components, UK) Powdered graphite is used as a lubricant for lighting equipment manual focus / adjustments. 
Liquid lubricants such as WD40 should not be used on any equipment that gets hot. 

Grelco (2 x 5A sockets to 5A plug)  (From the Museum of Old Electrical) (UK) A 2 way 5A or 15A electrical splitter, originally manufactured in the UK by Grafton Electric Company (hence the name Gr el co). Another name is SNAPPER (brand name) or in the US "TWOFER". Sometimes shortened to GRELLY. A three way splitter is known as a TRELCO, TRELLY (or THREEFER in the US). These splitters are always wired parallel (voltage equal, current shared).
See SERIES SPLITTER which enables (for example) two 115V lamps to be connected to a 230V supply.
[updated courtesy John Creed, 2017]
Museum of Old Electrical Items - Grelco

A scaled plan (overhead) view of the theatre stage area or of a set design, to enable all technical departments to ensure that everything will fit correctly into the space available. The groundplan shows all items standing on the stage floor and any permanent items which will affect the production, and the position of any flown pieces. The set design groundplan enables the lighting designer to be clear about exact location of all items, and will have the walls of the stage drawn on it so that the stage management team and production manager can plan furniture and set moves offstage.
Typical scales are 1:24 (.5' to 1 foot) or, metrically 1:25 (1cm to .25m). Venues have a base plan showing proscenium, walls, seating etc on which individual set and lighting plans can be drawn.

1) A long piece of scenery positioned at the base of a backcloth usually to mask the very bottom of a cloth or lanterns lighting a cloth.
2) Compartmentalised floodlight battens at floor level used to light the bottom of skycloths etc, often masked by groundrow scenery. 

A subdivision, permanent or optional, of a lighting board control preset, or a sound desk.

Function on Zero 88 lighting desks where all fixtures that are in a particular group type (during setup), can be sequentially connected (patched) to control channels. 

Philips GU10 LED lamp (4.6W) A type of domestic lamp which consists of an integrated lens & reflector built around the light source. The electrical connection is via two pins. Now available as LED, but was originally either a low-voltage (12V 50W) lamp used in birdies which featured a dichroic reflector, which passed heat through it rather than reflecting it, resulting in a colder beam, or as a mains voltage version. 

(from 'Halo') The spreading of light beyond it's normal boundaries to form a fog around the edges of a bright image. 
Halation - Color Theory

A 500W lantern (usually Fresnel or PC) - K refers to Kilowatt (1000 Watts).

Chemical process occurring in Tungsten Halogen lamps which makes them possible. During the lamps life, Tungsten evaporates from the filament, and would normally deposit itself on the glass wall of a Tungsten lamp, causing it to blacken, and causing the output of the lamp to reduce until it finally blew. In a Tungsten Halogen lamp, the Tungsten combines with the Halogen gas elements present in the lamp envelope and is re-deposited back onto the filament. This process needs a very high temperature to operate, so Tungsten Halogen lamps are able to be a lot smaller, and run a lot hotter, than their Tungsten equivalents. See also Tungsten Halogen.

Avolites term for the channel fader and the buttons below it, which are used to control a channel.

The 'hang' is the American equivalent of the lighting rigging session in the UK - the time when the lighting equipment is rigged.

A non-dimmed power supply to a lighting rig (or part of a rig).


(Trade Name) Range of 1000W lanterns produced by Rank Strand (now Strand Lighting) in the UK.
Strand Lighting website
Strand Archive

Family-owned and run technology company, founded in 1945 and headquartered in Germany. 
The brand is known in technical theatre for their heavy-duty multipin connectors used as 'Lectriflex'. 
Harting Website


Electronic platform for LED lighting developed by ADB and Claypaky in conjunction with Osram. 
The LED light source consists of a module with 6 colours: Red, Green, Blue, Amber, Cyan, Lime.
The additional colours mean HCR fixtures can achieve a CRI value of up to 99 (typically 97). 
HCR technology is used in ADB fixtures Orkis, Klemantis, Oksalis. 

US equivalent of the UK CHIEF ELECTRICIAN

The top lantern on a lighting boom. See SHINS and MIDS.

A shouted warning (often just 'Heads!') for staff to be aware of activity above them. Also used when an object is being dropped from above.

1) General term for theatre communication equipment.
2) A headphone and microphone combination used in such communications systems with a beltpack.
See also CANS.

Made by Rosco, Heat Shield is a special clear gel which when placed between a lamp and a coloured gel, dissipates a large amount of heat to give the gel a longer life. There must be an air gap between the Heat Shield and the gel, or it will not be effective.
Rosco website


Abbreviated to HTP, this is the standard by which some lighting desks operate.
If there is more than one control on the desk affecting a particular channel, then the highest level of the controls will take priority and affect the output of the desk and the dimmers.
This system is universal on manual lighting desks, but there are problems with the control of moving lights, scrollers etc, when more subtle variances in level are necessary, and LTP (Latest Takes Precedence) control is required. 

HMI (Hydragyrum Medium arc-length Iodide)
A mercury-halide discharge lamp with a colour temperature of 5600K (daylight).

A trademarked system for achieving high-brightness 'holographic' projection effects. Patented by Stuart Warren-Hill. 
HoloGauze Patent, 2017

On some lighting desks, the default position / intensity / status for any fixture or dimmer can be set, so you can easily reset a wayward fixture to where you want it to be, or to a position where you can set it to a new location / colour easily. Also useful for fault-finding, and for getting everything to a known position either at the end of the day, or when plotting a new cue. 

Hook Clamp 50mm (Doughty Engineering) A clamp with a wing bolt for hanging a lantern on a horizontal lighting bar, so that it hangs below the bar.
Introduced in the UK in 1959 by Strand, replacing the 2-bolt and 2-nut L Clamp.
Hook Clamps should not be used to overhang items above a lighting bar. A BOOM ARM can be rigged on a lighting bar (horizontal) or a boom (vertical) to rig a lantern adjacent from the bar / boom. 
Alternative clamps are available from companies such as Doughty to rig a lantern above a bar. 

A Hook Up is paperwork generated by the Lighting Designer for a show. It lists connections or layouts between number systems. For example, a Channel Hook Up lists the channel numbers used on the lighting plan alongside the dimmer numbers into which they're connected, and a brief text description of that channels function.

One of three connections on an audio or power connector. 
Hot - the 'live' or positive or signal cable, often coloured red
Cold/Common - the 'neutral' or return cable to complete the circuit
Ground - the 'earth' or ground connection which ensures electrical safety. In an audio connector is this often connected to the metal sheath of the cable. 

See Patching.

Refers to a 'live' power feed, which does not go via a dimmer. 
Many modern pieces of equipment used in a lighting rig must not be supplied with power from a dimmer (e.g. projectors, moving lights, LED lanterns etc). They require hot power, and have an additional control input connection (DMX512) which gives them instructions what to do. 

The brightest part of the beam from a lantern, usually showing the centre. Profile lanterns have a Field control which enables a beam to be flattened so it has no hot spot.

The auditorium lighting which is commonly faded out when the performance starts, and raised again at the end of the show, and during intervals. The House Lights need to be bright enough for the audience to find their seat, to read their programme, and find their ice-cream spoon, but should still set an atmosphere. As well as the functional house lights, if there's no house curtain, there may be a preset on stage, which helps to set the tone of the show, and to reveal part of the set that looks interesting. If there is a curtain, it will usually be cross-lit in a colour to make it look interesting. 

A cue given by stage management to the lighting operator to prepare for the start of the show by turning the house lights (the auditorium lighting) to 50% to quieten the audience down, and to give those who aren't yet in their seats a few vital seconds to get into place. 

(After Howard Eaton) This is a two circuit (two colour) 120V per circuit MR16 (PAR 16) batten developed by Howard for lighting cloths at close proximity. A row of these hung above a cloth allow you to light the cloth where there is little space. They have also become popular as footlights. The battens are designed to be used in pairs on a 240V (UK) power supply, connected via a series splitter to share the 240V down to 2 x 120V battens. They are also known as MR16 Battens or L&E Battens (after the manufacturer). 
Howard Eaton Lighting Ltd. website

Initialism for High Performance Lamp, the proprietary lamp designed for the Source Four by Entertec. The HPL uses a compact filament (with 4 filament strands, hence the name Source Four).



The colour of a light, costume or piece of scenery (etc.). 
The term is usually linked to Saturation, which is the amount of that colour. 

Acronym for International Code of Practice for Entertainment Rigging.
A new standard, published in 2017.
Download ICOPER at PLASA

IEC / NEMA connectors International Electrotechnical Commission. The UK mains inlet connector / 'kettle lead' is known as an IEC LEAD.
IEC website

Acronym for the four palettes used to control moving lights. Intensity (brightness of the beam), Focus (position of the beam), Colour, Beam (focus quality of the beam - hard-edged, soft-edged, or split through a prism).

Acronym for Insulated-Gate Bipolar Transistor. Electronic component used in later generation lighting dimmers. 
Wikipedia entry

International Laser Display Association
ILDA website

Short for Image Magnification - the use of live feed video cameras and huge video screens to bring the details of an artists' performance to a huge stadium-sized audience.

A term for the electrical resistance found in a/c circuits. Affects the ability of a cable to transmit low level (e.g. sound) signals over a long distance. Measured in Ohms. Speakers are rated according to power handling capabilities (Watts, W) and impedance (Ohms).

Theatre in the Round is a form of audience seating layout where the acting area is surrounded on all sides by seating. There are often a number of entrances through the seating. Special consideration needs to be given to onstage furniture and scenery as audience sightlines can easily be blocked.
Stage managers and directors often use the idea of a clock face to describe actor positions on stage (e.g. the aisle nearest the technical point is described as the 12 O'clock position, with other aisles described as 3, 6 and 9 O'clock.)

Light source consisting of a metal filament (Tungsten) which glows white hot when current is passed through. See also Discharge Lamp.
How do Incandescent Light Bulbs Work?

1) An electrical power supply that is totally separate from the stage lighting control. Used for testing lanterns prior to connection to the lighting system and also for powering non-lighting equipment on stage and working lights. See NON DIM.
2) A channel within the stage lighting control which has been temporarily switched to become independent from the rest of the channels which remain under the control of the operator.

Also known as a CORPORATE. An event or performance staged by a manufacturer or company in order to launch a product or celebrate a milestone of some kind. Such events are often spectacular.

Invisible part of the electromagnetic spectrum with a longer wavelength than visible light. Infra-red remote controls are used for lighting desks and practicals. An infra-red-sensitive CCTV camera can pick up body heat activity even in a 'blackout'.

A way of taking control of a rogue lantern (or lanterns) at the lighting desk during the operation of a show and removing them from any further lighting states, until the inhibit is removed. Can also be used for removing the front of house lighting from a curtain call state. See also SUBMASTER.


1) An additional route into a sound desk.
2) An extra lighting state added into the sequence later. See POINT CUE.

1) An electrical system in a particular building (e.g. "the stage lighting installation was tested last year")
2) A piece of art designed to transform a particular room or building into something other than a room in an art gallery. Installations often use complex audio-visual equipment and can be intensely immersive experiences. (e.g. "In the studio space this week we have an installation by John Doe entitled 'Space'")

(US) Same as a LANTERN or LUMINAIRE in the UK/Europe.

A list of the instruments / lanterns used on a show.
Usually sorted by hanging position (e.g. Front of House, First Electric etc.).


(Lighting) A way of describing the brightness of a stage lantern. A lantern supplied with the maximum amount of electrical power a dimmer is able to produce is described at being 'at full intensity' - this is often called '100%' or just 'Full'. 
As the electrical supply is reduced, the light gets dimmer (lower intensity). When the dimmer has been faded down (or 'faded out') the intensity is said to be '0%' or 'Zero' or 'Out' or 'Off'. 

A Scaffolding bar (aluminium) which has a number of sockets (usually 15A in the UK) positioned along its length, the wiring for which is contained within the bar.
Lighting bars nowadays need 'hot power' sockets and DMX outlets, as well as the more usual dimmer output sockets into which traditional theatre lighting equipment is connected. 
Bars in new theatre installations sometimes use 16A CEEFORM sockets which are more widely used in TV/Film studios, and are more universal than the 15A socket, which is UK-only. 
See also SIX LAMP BAR.

The Inverse Square Law, when applied to light, states that as light loses energy as it travels, the further you are from a light source, the dimmer the light source becomes.

Iris Diaphragm from a Strand Electric Pattern 23 Profile lantern Adjustable aperture which, when placed in the gate of a profile lantern, varies the size of a beam of light. Originally, iris diaphragm.
Most followspots have an iris permanently installed.
The term 'Iris In' means to slowly close the iris of a followspot so that the size of the beam is reduced, until as the beam gets as small as it can go, fading (or snapping) to blackout. The speed of the movement will depend on the pace of the show / music at that point. 
Profile moving lights have iris functionality built-in, and can be adjusted in beam size. Some wash moving lights have a zoom function which reduces the size of the beam. 

Type of multipin connector used on some lighting desks for analogue outputs.
CINCH website

Czech scenographer (1920 - 2002)
Josef Svoboda in the Backstage Heritage Collection Archive

An adaptor from one type of electrical connector to another. For example, a 13 - 15A jumper has a 13A plug and a 15A socket at either end of a short cable. Also applicable to sound cables.

Lighting Industry Forum code which identifies the (original) recommended usage of different lamp types. K coded lamps are for use in general purpose flood lighting, and have a colour temperature of 2850°K. See also CP, A1, T, P2.
Lamps List

The Jem K1 Hazer is a high-performance hazer produced by Martin. It provides the combination of continuous operation, long hang time, and low fluid consumption for greater economy.
Martin Website


A section on a lighting or other technical layout plan, which denotes what the symbols on the plan refer to. 
Although many symbols are standardised, there are variations, and to avoid confusion (or errors) when rigging and laying out equipment, a key is essential to ensure the requirements of the design are correctly interpreted. 
Lighting Paperwork

(Esp. TV & Film lighting) The dominant light source/direction in a naturalistic lighting state. In a sunny drawing room, the key light would be through the window, for a naturalistic exterior scene the direction of the key light could change as the sun progressed across the sky. See FILL LIGHT.

A function available on data projectors which allows the selective stretching of the horizontal component of the projected image so that it appears to be rectangular when projected from an angle above or below the projection surface. More advanced (expensive) projectors can also keystone the vertical component of the image, and some recent projectors can automatically detect the projection surface and can automatically keystone the image to fit.
Before data projectors, special lenses were available for slide or film projectors to apply the keystone effect.
The term comes from the wedge-shape of the stone placed at the top of an arch to spread the load of the wall above equally down both sides of the arch.

Lanterns placed to the side of the actor to maximise the sculptural quality of the light are sometimes known as KICKERS.

To switch off (a light/sound effect); to strike/remove (a prop).
(e.g. Kill channel 6 please)

1 kilowatt (1kW) is equal to 1000 Watts. The WATT is a measure of electrical power. The single letter 'k' is often used to represent 'kilowatt'. "2k fixture" means a 2000 Watt (or 2kW) lantern etc.

1) General name for equipment, especially nice shiny equipment, leading to the comment 'That's a nice bit of kit'
2) Short for Drum kit.

A type of animation disk which fits into the colour runners at the front of a lantern which rotates and breaks up the light beam to make it appear to be moving. Best used on a profile lantern containing a gobo. A KK Wheel is known in the US as LOBSTERSCOPE.

Named after brothers John and Anton Kliegl, the Klieg Light was originally an intense carbon arc lamp especially used in filmmaking. Modern Klieg lights use Tungsten Halogen lamps. Klieg lights are either fitted with a fresnel lens and spherical reflector (for a wash of light) or a single or pair of plank-convex lenses and an ellipsoidal reflector for a spot light.

Kilo-Volt Amps. Unit of electrical power.

1) Climbable piece of access equipment to reach a working platform or for short light-duty work at height. See ZARGES.
2) Non-climbable structure in the shape of a ladder from which lanterns can be hung in a vertical 'stack'.

A Lady and the Tramp moment occurs when two people clearing and coiling LX or sound cables end up both coiling the same one. Named after the Disney classic animation where two dogs end up eating the same piece of spaghetti.

A light bulb is used in domestic situations (i.e. in the home). In the industry, we only use LAMPS. As the saying goes, 'Bulbs is what you put in the ground'.
Example usage: 'The lamp in the DSC fresnel has blown'. In the TV/Film world, a lamp is called a BUBBLE or GLOBE.

Part of a stage lighting instrument which contains the light source, electrical connections and (often) the bracket to attach the lantern to the lighting rig. 
Different lens tubes can be connected to a lamp house (as long as they're by the same manufacturer) so that the lantern is suited to the application for a particular event / show. 

A command sent over DMX512 from lighting control consoles to moving lights which have discharge lamps. When the moving light is powered up, the lamp is usually set to power on, and remains lit, whether the moving light is in use or not. This is wasteful of energy, and of lamp hours, which are limited. If the moving light(s) are not being used for any length of time, the Lamp Off command can be sent to turn the lamps off. The lamp cannot then be relit for a period while it cools down. 

Periodic inspection of all light fittings around the theatre, to replace dead lamps / bulbs. Usually takes place before opening night.

Lower section of the body of a theatre lantern on which the lamp holder is mounted. Some lamp trays are hinged, some are removable from the rest of the body. Modern safety legislation (UK) requires that the lamp tray cannot be opened until power is disconnected.

(colloquial term) Theatre / Rock & Roll lighting technician. Distinct from a 'Techie' who may also be a carpenter or stage crew member. A lampy only concerns him/herself with lighting.
A more generic electrician might also be called a Sparky, or Sparks.

1) General term for unit of lighting equipment including spotlight, flood etc. Term now being replaced by the internationally recognised "luminaire" (esp. Europe) or "instrument" in the US.
See also FIXTURE and TYPES OF LANTERN link below.
2) Glazed section of roof usually in haystack form over the fly tower that automatically opens in the case of fire. An updraught is created which inhibits fire from spreading quickly into the auditorium, and prevents build-up of smoke at stage level.
Types of Lantern at

Acronym of Light Amplification by Stimulated Emission of Radiation. A very high energy beam of light that remains virtually parallel throughout its length. Visible in the air only when a haze of smoke or dust is introduced. Great care is required when using lasers as this energy can cause permanent damage to the retina of the eye.
How Lasers Work

Abbreviated to LTP, this is a standard by which some computerised lighting desks operate.
If there is more than one control on the desk affecting a particular channel, then the latest control to operate will be the one to affect the output on stage.
This system is used on desks with moving light functionality.

Acronym for Light Board Operator. Also known as the Board Operation (or Board Op).

Abbreviation for Light Centre Length. This measurement (in mm) is the distance between the top of the lamp base and the optical centre of the filament. This measurement is critical as it ensures that for a particular lantern, the filament is at exactly the correct position for maximum light output and efficiency. Many different lamp types exist, but there are far fewer lamp-base types, meaning it's possible to insert the wrong lamp into a lantern very easily, resulting in poor output and efficiency.
See also MOL.

LD / L.D.
Lighting Designer.

1) Light-Dependent Resistor. Electronic component used in a circuit to detect the presence (or absence) of light. Used in theme park attractions to detect a passing ride vehicle or in safety / security systems to detect movement past a particular point. 
2) Italian lighting manufacturer, founded in 1997.
LDR at Backstage Heritage Collection

(Manufacturer) UK based manufacturer of pyrotechnic devices (Pyroflash brand name), smoke machines and other theatre effects
Le Maitre website

6 way Lectriflex Plug Spider (15A plugs to Multi-way Lectriflex connector) from White Light Multipin connector for carrying multiple lighting circuits down a multicore cable. See also SOCAPEX.

LED / L.E.D.
Red LED (RS Components) Light Emitting Diode. LED technology has transformed stage lighting, at a time when energy efficiency is at the top of many agendas. The best LED luminaires for theatre are, however, still expensive, but getting cheaper. Cheaper units have noisy fans and may have issues with flickering on video recordings of shows, as well as poor dimmer curves and low CRI (colour rendering index) values. 
LED light sources are extremely efficient, and give off very little heat, making them ideal for display or architectural work. LED video walls are in use all over the world - they are more efficient and lighter in weight than projection alternatives.
The LED Museum
How LEDs work

(Manufacturer) UK based manufacturer of lighting gels. See COLOUR FILTER.
Lee Filters website

Strand Lekolite 8 x 13 A type of ellipsoidal profile spot (aka ellipsoidal reflector spotlight or ERS), much used in the USA. Originally designed in 1933 by Joseph Levy and Edward Kook, the founders of Century Lighting (later Strand). The word is a contraction of their names (Levy & Kook). Also known as LEKOLIGHT.
Leko in the Backstage Heritage Collection archive

Optical glass with one or both sides curved, the purpose of which is to direct light by concentrating or dispersing light beams.

An assembly of more than one lens in a piece of lighting or camera equipment. The lenses are usually adjustable relative to one another to enable the size or focus of the light to be altered. 

Part of a stage lighting instrument which contains the lens(es) and focussing adjustment controls, and the colour frame holder at the front of the instrument. 
On some instruments, the lens tube is a fixed part of the lantern. On others, it's interchangable and different lens tubes can be connected to the same lamp house (containing the lamp, and rigging equipment to hang the lantern on the lighting bar). 

1) The setting of a light or sound control channel. On a lighting desk, levels range from 0% to 100% (also known as FULL). On a sound desk, the bottom of the fader is ∞ (infinity) and the top may be +20. The fader is designed to be operated at it's optimal position which is labelled 0dB. The decibel (dB) scale is a measure of sound intensity. 
2) A platform used to change the height of an actor. Interesting dynamics between different characters in the play can be explored using various levels. 

How Light Works


Light Curtain (Svoboda Batten) A lighting effect which, when an area is diffused with smoke, produces a wall of light. Produced (usually) by a batten of closely-spaced low voltage lamps wired in series.
Automated versions are available which have colour changers built-in and are able to tilt up and down. The original Light Curtain designed by Josef Svoboda is still made by ADB. (See SVOBODA, DIGITAL LIGHT CURTAIN)
Light Curtains in the Backstage Heritage Collection

Danish slang for Lighting Designer.
Submitted by Erling Larsen

Member of the show crew who runs the lighting board during the show for the Electrics Team. Also known as LBO (Lighting Board Operator).

A scale drawing detailing the exact location of each lantern used in a production and any other pertinent information (E.g. its dimmer number, focus position and colour number). Often drawn from the theatres' groundplan.
Lighting Paperwork

1) The process of recording information about each lighting state into the memory of a lighting console for subsequent playback. (in USA, this term is used for a lighting plan and a lights session is when lighting states are set up.) The lighting designer communicates with the board operator, often via a comms headset, who physically types the information into the console. 
2) See also LIGHTING PLAN. 

Usually three-legged telescopic stand on which lighting equipment can be mounted. The stand will have a socket on the top into which a spigot can be inserted, which is bolted onto a single lantern. Or, a spigot can be attached to a scaffold clamp or a T bar to enable multiple lanterns to be rigged. Ensure the lighting stand you are using is strong enough for the lanterns you want to rig. 

The format of lighting used at a particular point in the production; a lighting 'picture'. A lighting cue is given by the stage manager which initiates the change from one lighting state to the next.

Plastic stencil containing a range of scale symbols for current lighting equipment. Greatly facilitates the drawing of lighting plans.
Lighting Stencils on the Backstage Heritage Collection

Club / DJ control and visualisation software by Martin.
Martin website

1) Announcement by the DSM that a section of the performance has ended (e.g. Lights Down on Act One).
2) A reduction in light level - usually a note by the lighting designer for her/his own reference.

1) Announcement by the DSM that a section of the performance has begun (e.g. Lights Up on Act One). An alternative to Curtain Up.
2) An increase in light level - usually a note by the lighting designer for her/his own reference (e.g. Lights Up when the waiter enters the kitchen). See also FULL UP FINISH

An obsolete source of intensely bright light, most recently used in followspots.Derived from a burning jet of oxygen and hydrogen impinging on a rotatable cylinder of lime.

Followspots and their operators. This term is still in everyday use, although limelight is not. See also PICK-UP.

A connection between two lighting or sound cues which are not numerically adjacent. 
If, for example, the lighting designer wants to simplify a cueing sequence which is not working, the cues at the start and end of the sequence can be linked together in the lighting desk so that the sequence is jumped over. Similarly if the director cuts some lines which affect a cue. 
See also POINT CUE.

Optically simple lensless system for projecting a shape from a gel or glass slide etc. onto a set or cloth. The slide is placed in the front runners of the projector which is a floodlight (with a point source lamp, and no reflector). Often used for shadow effects or simple scenic projection. The projector was developed in Germany by Adolphe Linnebach (1876-1963) in 1916 at the Court Theatre, Dresden. In order to get a sharp image, the lamp filament should be as small and as bright as possible, with adjustment to move it towards and away from the slide. A high intensity low voltage lamp is often used for this purpose.
See also OLIVETTE.

Little Tom Clamp, Doughty Engineering A clamp made by Doughty Engineering, to enable a scaffold pole to be used at the top of a standard telescopic lighting stand to support two or more lanterns, or to form a vertical support for a longer scaffold pole to hang masking curtains or lightweight scenery cloth from. 

This is the normal mode for operation for lighting control desks, where any changes made are instantly reflected on stage. 
Many lighting control desks have a BLIND mode, where changes can be made without affecting the current state. 

1) The electrical power rating, in Watts, of the equipment connected to a particular lighting dimmer. 2) The equipment connected to a dimmer.


Lobsterscope (Brenkert) A mechanical device that reproduces the flashing 'motion-freezing' effect of a strobe. Consists of a metal disc with at least two oval or S-shaped cutouts opposite each other, which when spun electrically or by hand produces a smooth strobe-like effect, and can also (at slower speed) suggest a passing train or other motion.
See also KK WHEEL.

A neatly-organised bunch of cables. A wiring loom is used to avoid messy runs of cables by keeping the cables going in the same direction (to the same piece of equipment) tied together. This saves time when installing and packing-down equipment, and ensures that a piece of cable can't be mislaid or left behind. 
The cables can be taped together (using PVC tape, never Gaffer Tape) or, for more long-lasting arrangements, with cable ties. More environmentally-friendly companies use short lengths of rope for the same purpose, which are re-used over and over again. Strips of rubber can be used for the same purpose. 
The looms are named according to their purpose (e.g. the Control Loom goes from the control desk to associated equipment, and may contain a power cable, a communication cable and a DMX512 cable for the control signals). 
Known as a 'hod' in the USA (apparently from old French term for intestines).
Also known as a TRIPE. 

Smoke that has been chilled as soon as it comes out of the smoke machine. This causes the smoke to lay close to the floor. Use fast dispersing smoke for this effect because when the smoke heats up in the air, it will rise.
Low Smoke is much safer to work with than DRY ICE, which produces a longer-lasting effect but is more expensive.
Fog / Smoke / Haze On Stage

Lower voltage lamps give more intense light than mains voltage lamps of the same wattage.


Lua is a programming language that can be used on versions of MA software (for the GrandMA range of lighting consoles). 

A measure of light output from a source. The brightness of video projectors is stated in Lumens.
See also LUX.
What Lumen rating projector should I use?

The international term for lighting equipment. Not restricted to theatre lighting.

A measure of the level of illumination on a surface (1 lumen spread over 1 metre).

Short for Electrics ('Elecs'). The department in the theatre responsible for stage lighting and sometimes sound and maintenance of the building's electrical equipment. Lighting cues in the prompt book are referred to as LX cues (abbreviated to LXQ).
(In the USA, LX cues are known as Light Cues, and may use LQ instead of LXQ). 


A range of professional moving lights made by Martin in Denmark.
Martin website

A shortcut that can be user-created on software-driven devices (e.g. lighting desks, sound desks) that carry out an often-repeated set of commands at a single button press. (e.g. 'I've created a macro to stop the effects on the downstage moving lights'). A macro is first 'learned' - when in learn mode, all button presses are memorised, and can then be stored as a numbered macro, or to a specific macro key.

A smaller version of the lighting plan, used by the lighting designer during the lighting plot. Also known as a Dimmer Layout or Cheat Sheet.
Lighting control software can produce an electronic version of the Magic Sheet, which can be laid out however works best for the lighting designer, and provides shortcuts to groups of lanterns, effects and colours.

See Secondary lighting.

A lighting desk where the interface between operator and dimmer is a fader, rather than a computer. Many modern manual desks have some memory facilities built in, but there are still a large number of venues with solely manual systems.

(Abbreviated to MBB) A timing measurement within a DMX signal. Variations in timings and DMX speed can cause problems on some older or not-totally-compliant DMX controlled lighting equipment. 
ETC FAQ on DMX Speed

An electrically detonated pyrotechnic device giving the effect of a loud explosion. Made from gunpowder encased in stout cardboard or string. Must be used within a metal bomb tank. Originally developed in the second half of the 19th century to simulate the sound of cannon, it was often used to call out the volunteer lifeboat crew in an emergency.

1) Form of theatre where actors faces are covered with masks.
2) Early word for GOBO.

1) An overall control fader or lever on a lighting or sound control board. The Grand Master takes precedence over all other controls and allows the operator to fade out the entire output of the lighting desk.
On a lighting desk the PRESET MASTER allows the control of a section of the desk independently from the rest.
2) An original (e.g. Master tape, master plan) which should be used only to make a copy from which to work.
3) A Department Head (e.g. Master Carpenter, Master Electrician).


Moving Light console produced by Martin.
Martin website

Metal Halide discharge lamp. See also DISCHARGE LAMP.

Hager 32A MCB (from TLC Direct) UK Minature Circuit Breaker. Up to 63A (UK).
A resettable fuse, which trips to cut the flow of electrical current when too much current is detected. This may happen due to an electrical fault in a particular piece of equipment, or may be due to a lamp blowing (the bright white flash when a lamp blows is caused by a short-circuit across the lamp contacts, which draws a large amount of current briefly, until the MCB trips). 
See also FUSE.

Moulded Case Circuit Breaker (over 63A - UK). See FUSE.

"Meatrack" / Transporter Trolley (Doughty Engineering) Heavy-duty wheeled rack with inbuilt supports or bars for transporting a number of pre-rigged six-lamp bars or lanterns.

A lighting control which enables recording and subsequent 'playback' of lighting states. 
Now commonplace, and in some cases rendered unnecessary as lighting control moves to standard laptops running software such as ETC's EOS. 

The middle lantern on a lighting boom. See SHINS and HEADS.

The VDU associated with most medium and large lighting desks has a detailed mimic of the level of all dimmers and other associated information.

(Trade Name) Range of 300W lanterns produced by Rank Strand (now Strand Lighting) in the UK.
Strand Lighting website
Strand Archive

(Trade Name) Range of 500W/650W lanterns produced by CCT in the UK.
CCT Lighting website

Large plastic sphere covered in a mosaic of small mirrors, which reflect light outwards, to cover the area with bright dots of light. Usually suspended by a rotator (an electric motor which turns the ball). Can be very effective when lit by pinspots, or more commonly now, intense moving light beams.

Although the term literally "placing on stage" in French, the Mise en Scene refers to much more than the setting of a performance or event. The term describes all of the visual aspects of a setting - props, lighting, costume as well as set design, and how the details can contribute to the telling of the story.


(often abbreviated to MEWP) A piece of access platform with a wheeled base, which can sometimes be self-propelled by the operator. The best known manufacturer is GENIE.

(Lighting) An attachment for a photographic / film light source which alters or modifies the light, by making it softer, or reflecting it. 
Common modifiers are silver umbrellas and softboxes. 

A type of lamp base, designed for heavy-duty applications such as high level lighting in warehouses etc. The Mogul base larger than standard domestic lamps is designated E39 (which is 39mm wide). 
See also E.S. and G.E.S.

Abbreviation for Maximum Overall Length. This measurement (in mm) is the length between the ceramic lamp bases at each end of a double ended (linear) lamp, such as that used in floods and some discharge lamps.
See also LCL.

(Trade Name) Multi-lamp flood lantern made by Mole Richardson, used for washing large areas of stage with colour, or as an audience 'blinder' for a concert. Sometimes fitted with colour scrollers for maximum flexibility. One option consists of 8 x PAR 36 ACL (AirCraft Landing) lamps, but there are many different configurations. 
The instrument is named after Mole Richardson and the FAY lamp type, produced by General Electric. The FAY is 650W 120V with a frosted front lens. 
Molefay in the Backstage Heritage Collection

1) An onstage speaker which allows a performer to hear the output of the PA system, or other members of a band.
2) A video display screen (not normally able to receive broadcast TV pictures) used with a CCTV system or a computer.

(Lighting) Describes a filament inside a lamp between two terminals, meaning the filament is in a single line (or a single plane).

Lighting effect. A large shallow circular box with calico cloth on one face and low wattage lamps arranged on the back. Can be flown behind a gauze or thin cyclorama to give the effect of the moon rising.

A function on modern computerised lighting control desks which automatically manages moving lights which are turned off between cues in which they're in a different position setting. Once the moving light fades out, the lighting control desk will automatically move it to its' new position, before it turns back on again (as long as the blackout or cue between is long enough). 
On ETC consoles running EOS software this function is known as Auto-Mark. 


Remotely controllable "intelligent" lighting instrument. Each instrument is capable of a massive variety of effects which are operated live via a moving light control desk, or can be pre-programmed by a standard memory lighting desk. The instruments require a power supply and a data cable (normally carrying DMX512 signal from the control desk).
There are broadly two types:
1) Moving Head: A luminaire is mounted on a moving yoke which can pan side to side and can tilt the luminaire through a range.
2) Moving Mirror: A stationary luminaire directs light onto a motorized mirror.
Both types have in common:
- A discharge (non-dimmable) light source or dimmable LED source (rare variants use a tungsten source, but most new moving lights are now LED-based)
- A dimming shutter (for discharge light sources)
- Motorized rotating colour wheels. Some offer colour mixing using graduated red, green and blue wheels or prisms.
- Profile versions have motorized gobo wheels with rotation.
- Strobing effects and adjustable iris. Some also have framing shutters.
The term "intelligent" is used as the instrument has a processor chip and electronics built into it, not because it's able to interpret the designer's artistic intent! It can be incredibly frustrating trying to get moving lights to behave exactly as required in a dramatic situation. Musicals and live music performances are more forgiving.
Moving Head lanterns are sometimes known as NODDING BUCKETS, Moving Mirrors are sometimes known as WIGGLIES or SCANNERS.


A 12 Volt lamp dichroic lamp commonly used in place of a Par 16 lamp in BIRDIES. See BIRDIE.

Philips MSD250/2 Lamp Metal-Halide discharge lamp, generally used in 150, 250, 400, 575 and 1,200 watt ratings. Found in film/tv lighting, and in some intelligent / moving lights.

Material Safety Data Sheet. Form available from manufacturers of, for example, smoke fluids. Lists any hazardous ingredients and other safety-related data about the product.

Philips MSR700SA Discharge Lamp (Medium Source Rare earth) High efficiency discharge lamp with a high colour temperature (approx 5600°K). Provides around 50% more light output than a incandescent lamp of the same wattage.

Short for MULTICORE.

10m 8 way Microphone Multicore Cable from A flexible electrical cable composed of many well-insulated sets of cables covered in a strong PVC or rubber covering. Enables a number of different circuits to be carried down one piece of cable. Both lighting (power) and sound (signal) multicores are available.
Sometimes known as a Multi or Snake.


All modern lighting desks use this serial form of communication with dimmers and other equipment. Information from the desk is transmitted along a single pair of cables in sequence to the dimmer where a de-multiplexing unit (demux box) decodes the string of data and passes the correct piece of information to the correct dimmer.
The industry standard protocol (language/standard) for multiplexing is the digital USITT DMX512 (introduced in 1986, based on RS485 data protocol, and often shortened to DMX or DMX512). However, new protocols are continually being added to keep up with more demanding equipment.
Although the standard connector for DMX512 is a 5 pin XLR, as the system only uses 3 connections, a great deal of equipment uses the more common 3 pin XLR. Care should be taken when using standard microphone cables to connect devices using DMX512, as the cable is usually less capable of accurately transmitting the digital data than a more expensive DMX512 cable. Short runs with microphone cable are acceptable.
As the basic DMX512 standard is one-directional, there should be a DMX terminator at the end of the DMX run to absorb the data signals and stop them being 'reflected' back down the cable and causing communications errors and other problems.  
SMX (Strand Multiplex) is a communications protocol which enables digital dimmers to "report back" to the desk on any faults (eg blown lamps).
RDM (Remote Device Management) is an emerging upgrade to DMX512 which will include bi-directional communication between controller and device.
DMX512-A (officially ANSI E1.11) is a new standard under development at ESTA which is backwards compatible with DMX512 but has stricter safety parameters and offers some upgrades of functionality.
Among the older protocols (before DMX512) are:
AMX192 Introduced by Strand Lighting around 1975, and later used on the CD80 dimmer range. AMX stands for Analogue Multiplexed Signal, and can control up to 192 channels, using a 4-pin XLR connector.
CMX - Colortran Multiplexing Signal, also known as D192. Developed in the late 1970s and first used on the Channel Track console. Uses 5 pin XLR, and is a digital multiplexed signal (rather than the analogue multiplex that AMX used). The signal is RS422.
D54 which uses a stream of analogue voltage levels and was the Strand standard, controlling up to 384 dimmers. First introduced on Galaxy desks.
See also UNIVERSE.

NC / N.C. / N/C
1) (US) No Color (US equivalent of UK's OPEN WHITE).
2) Not Connected (in a circuit diagram).

1) A type of discharge lighting generated by a high voltage across two oppositely charged electrodes at opposite ends of a long, thin glass tube filled with neon gas. As the electrical charge flows between the electrodes, electrons collide with neon atoms causing them to give off energy in the form of visible light. Different colours can be obtained by mixing other gases, or by using fluorescent coatings. Mostly used for advertising signs - the glass tube is bent to form letters.
2) A small mains voltage indicator lamp.

(ND) Lighting filter which reduces the brightness/intensity of a light source without changing its colour value. Used extensively in TV/film for reducing the intensity of discharge lamps or natural light sources (e.g. windows). Rarely used in theatre as dimmers fulfil a similar function (although as incandescent lamps are dimmed, the colour temperature gets warmer).

(Manufacturer) Brand of zoom profiles & followspots with halogen or HMI lamps. Very popular in Europe. Named after Emil Niethammer.
ADB website
Submitted by Andre Broucke

Channels, usually controlled from the lighting desk, which are switched, rather than dimmed. This enables motors, slide projectors, smoke machines etc to be controlled from the lighting desk. 
Older dimmers can be setup so that the channels go straight to full from zero at a particular channel level (e.g. 50%). However, these may not provide a properly switched output, as they are still using the output from a dimmer at full, rather than the output from a relay circuit (or switched circuit) which takes the power feed and bypasses the dimmer circuitry completely.

Network Processing Unit used with grandMA lighting systems. Interfaces between ethernet from grandMA desk(s) and DMX-controlled devices.

Compact light fitting designed to mount just above (or just beside) a film/stills camera lens for two reasons: firstly to create a characteristic glint in the eye of the subject of the photograph/film (it's known as the Eye Light), secondly to flatten out any lines/wrinkles in the face of the subject. The Obie Light is named after the actor Merle Oberon (known to friends as 'Obie'). It was first used by her husband, cinematographer Lucien Ballard, in the 1940s to make lines and shadows disappear from her face which were due to scarring following a car accident.
The Obie Light is normally heavily diffused.
Also known as a CATCH LIGHT
Mole Richardson Obie Light in the Backstage Heritage Collection archive

1) A movement towards the nearest side of the stage from the centre. (e.g. 'Focus that spot offstage a bit please')
2) The area out of sight of the audience (e.g. 'Get that donkey offstage !')

1) Abbreviation used by the Phantom in The Phantom of the Opera, when he writes letters to the theatre managers. Short for Opera Ghost.
2) Urban slang 'Original Gangster' or 'Old Git' (from, meaning a product which is now past its' prime, or was one of the first of its' type. 

The unit of electrical resistance.

[obsolete term] Lighting instrument using an incandescent lamp (usually mogul screw-base, 1000W). The lamp was usually mounted base-up, facing a large opening (the size of a full sheet of gel). Now used as a cyc flood, the instrument was originally designed for projecting painted glass images onto cycs. See also LINNEBACH PROJECTOR.
Submitted by Audrey Glickman

1) A movement towards the centre of the stage from the sides. The opposite of OFFSTAGE. There is no abbreviation for onstage (as it is too easily confused with offstage).
2) The act of being on the stage (e.g. 'he joined her onstage for the finale')

A lensless stage or film light. Most now must have some protection across the front to prevent injury / damage in the event that a lamp explodes / ruptures. The lack of a lens means there is limited adjustability to the beam, and the quality of light can be quite harsh. An example is the 800W Redhead, used for film/tv production. There is some adjustment to be beam by moving the lamp in relation to the reflector (using a control knob at the rear of the lantern) but the beam usually requires softening with some frosted gel or silk, or to be bounced off a surface or reflector, rather than being pointed at actors. 

(o/w) Lighting with no colour filter. Known in the US as NC (no color).


An arrangement of lenses or mirrors in a specific layout to guide a beam of light (or a line of sight) for a specific purpose. 

Electronic component which transfers electrical signals between two isolated systems using light. This helps to prevent damage from high voltage spikes, and also isolates troubling ground loops in audio or lighting control signals from affecting audio quality and integrity of the control signal. 

Outrigger An extendible leg to increase the stability of access equipment (eg Tallescope, Scaffold tower).

(Followspot term) The wider of two followspot beams covering the same performer.
(i.e. lamp one in a pink 'bust' (head-to-shoulder) and lamp two in a blue full-body overlay (head-to-toe).
Submitted by Bert Morris.

Lighting Industry Forum code which identifies the (original) recommended usage of different lamp types. P2 coded lamps are photofloods, and have a colour temperature of 3000°K. See also PHOTOFLOOD, CP, A1, T, K.
Lamps List

1) See PAGING.
2) Some theatre announcement systems use the term 'PAGE' to mean making a call (e.g. 'Can you page Simon to come to the fly floor')
3) A way of increasing the functionality of a control on a lighting desk. For example, most computerised lighting desks with SUBMASTERS will allow you to store more than one lighting state in each submaster. Each group of submasters is given a page number which is used to select which set you want to use. See also SUBMASTER.

(Obsolete) Brand name of a 1000W beamlight made by Strand Electric in the UK. Produced a near parallel beam and had a set of spill rings on the front to minimise glare.
A similar unit made by GB-Kalee was known as a VIGNETTE beamlight. 
Archive - Pageant

Connecting more than one lantern to one power outlet via an adaptor or splitter, or more than one speaker to one amplifier channel.

On lighting control systems, a palette is a collection of references for colour, position, beam type or intensity. Every cue or preset that includes the palette will be updated if the palette is modified.

1) A control on a mixing desk which allows the operator to position the channel's output in the final stereo image (L - R).
2) A horizontal (side-side) movement of a camera or a moving light. Short for Panorama. See also TILT.

PAR64 lamp lenses ( Short for Parabolic Aluminised Reflector lamp. A lamp containing a filament, reflector and lens in one sealed unit. Used in PARCANs to produce a high intensity narrow beam of light. Par lamps are available in many different sizes and powers. Par sizes available include 16, 36, 38, 56 and 64. (The number refers to the diameter of the lens, in eighths of an inch, so a PAR64 lamp is 8 inches across).
The most common for theatre use are Par 64s rated at 1000W (1kW), although other wattages are available.
When the lamp was first introduced, in the 1960s, it was only available from the USA in 110V versions. In the UK, Parcans were always used in pairs, via a series splitter. 110V Par lamps are still sometimes used in large UK venues or for touring due to the increased light output. Because the current is greater, the lower voltage lamps have smaller thicker filaments which give a more focussed beam than the thinner 240V filaments.
In the film business, PAR lamps are known as 'bird's eyes' after the alleged inventor Clarence Birdseye.


See PAR.

1) The folding frame that forms the base of a readily portable platform.
2) The opposite of SERIES when referring to wiring two loads into one outlet. The two loads share the available current, but are both given the same voltage.

Narrow PAR64 lamp (240V) and the beam it produces which is a projection of the filament of the lamp. Type of lantern which produces an intense beam of light, ideally suited to "punching" through strong colours, or for special effect. The Parcan is literally a cylinder of metal (the "can") within which sits the PAR lamp (PAR stands for Parabolic Aluminised Reflector) which consists of the bulb, a reflector and a lens in a sealed unit.
The PAR was originally available only as a 110V lamp, imported from the USA, where they were used as beam lights. The lamps were first introduced in the UK by concert hire company ESP in 1968 [Cue issue 1, page 14].
The Parcan was being widely used by the early 1970's in the Rock concert industry due to the intensity of the beam, and the light weight and near indestructibility of the lantern. The lens of the lamp is either clear (which produces a narrow beam), frosted (medium) or stippled (wide).
Parcan lamps are available in a range of different lens types:
UK (240V): CP60 is a narrow beam (clear lens), CP61 is medium beam (frosted lens), CP62 is wide beam (ribbed lens)
See also PAR and FLOORCAN.
Types of Lantern
Parcan Evolution and History

(ETC EOS Lighting Controls) The park instruction allows you to set a channel or parameter to a specific value and have it remain at that level on stage (live mode), prohibiting manual control override, cue or submaster playback modification.
To park channel 72 at zero, type 72 @ 0 PARK ENTER.
The standard keyboard shortcut for PARK is ALT+K.

ETC Parnel Brand name for a wash light manufactured by ETC. It's a cross between a soft-edged focussable Fresnel and a ETC Source Four PAR.
PARnel at the Backstage Heritage Collection
Types of lantern

Short for Portable Appliance Test. Requirement under the UK Electricity At Work Regulations (1989) to test and inspect all portable electrical equipment. This includes stage lighting equipment (lanterns, cables, portable dimmer packs etc.).

1) (verb) The act of plugging a lantern into a dimmer (e.g. 'Can you patch circuit 12 into dimmer 18 please') or on a lighting desk allocating control channels on the desk to dimmers or fixtures in the rig - this is known as a SOFT PATCH.
If written down, this is known as a Patch Schedule or Patch List. 
2) (noun) The system for connecting lanterns to dimmers (The Patch).
The term also applies to sound - a PATCH BAY is used to connect outboard equipment into the sound desk and to connect sound desk outputs to amplifiers, and amplifiers to speakers.

A board consisting of rows of sockets into which plugs can be connected to route sound signals or power for lighting circuits. Some American systems use a Pin Plug patching system. See also PATCH.

1) To cross-connect lighting circuits around the stage area to a chosen dimmer. Connecting lanterns to dimmers. This is sometimes known as a hot-patch (because you are potentially patching live power). The connectors used in a hot-patch system must not permit the user to touch live connections. 
2) Using a cross-connect panel which enables any stage lighting channels to the control desk to control any dimmer or group of dimmers. Some large lighting boards have the facility for soft patching - a totally electronic way of patching. Some Rock Desks have a pin patch which allows groups of dimmers to be allocated to a particular control channel. Also applies to routing of sound signals.

1) See GOBO.

Many older Strand lanterns are identified by their Patt. number (eg Patt.23 is a 500W profile). The numbers bear no direct relation to their size or type (although lanterns of a similar design may have similar Pattern numbers.) See for a complete listing.
TABS article by Frederick Bentham about the Pattern Numbering logic
Strand Lanterns with Pattern Numbers - Backstage Heritage Collection

Strand Quartet PC (500W) Originally short for plano-convex - the basic lens shape of many lanterns / projectors. Now short for Prism- or Pebble-convex: a type of lens with a pebbled flat surface which gives a slightly harder edge than a Fresnel, but not as hard as a Profile. PC refers to a lantern with a PC lens.
Types of lantern

See PC.
Types of lantern

Optical illusion effect used to make a ghost appear on stage next to an actor. A sheet of glass is hung across the front of the stage so that the image of an actor standing in the orchestra pit appears to float on stage. First shown at the Royal Polytechnic Institution in London by J.H.Pepper on Christmas Eve, 1862. Following many subsequent events, Charles Dickens used it during readings of The Haunted Man. Several plays were written specially to use the effect around 1863, but the long-term future of the effect was limited by the fact that the ghost couldn't speak.
Peppers Ghost is now used to great effect in smaller scale applications like the Haunted Mansion in Disney theme parks.

More about Peppers Ghost
Dark Rides at

Dimmer levels are expressed as a percentage of the supply voltage. (100% = 230 - 240 Volts(UK)).

1) A lighting position (often on a platform) at each side of the stage, immediately behind the proscenium.
Some theatres use the term for vertical boom positions in front of the proscenium in the house.
The plural is PERCHES. They may be named by position (e.g. Front Perch, Rear Perch, SL Perch etc).
2) An ancient unit of measurement, used since the 9th century, and abolished in the UK in 1963. One perch is equal to 16.5 feet, or 5.03 metres. 

A form of theatre which used a modified magic lantern to project frightening images such as skeletons, demons, and ghosts onto walls, smoke, or semi-transparent screens, frequently using rear projection. The projector was mobile, allowing the projected image to move and change size on the screen, and multiple projecting devices allowed for quick switching of different images. Invented in France in the late 18th century, it gained popularity through most of Europe (especially England) throughout the 19th century.

Electricity is generated and supplied to large installations as three separate supplies, known as phases, and labelled L1, L2 and L3 (for Line).
Until recently, the three lines were colour-coded Red, Yellow and Blue in the UK. Now, across Europe, the three lines are colour-coded brown, black and grey, with the neutral coloured blue.
Each of the phases and one neutral are supplied down a single multicore cable to the building, but effectively give three separate supplies. Because there is a potential difference (voltage) of 415 volts between any two phases and earth/ground, care must be taken that pieces of equipment powered by different phases are not capable of being touched at the same time in case of a fault.
This usually means that such equipment should not be on the same physical lighting bar, or in the same part of the studio theatre.

A family of medium to large computerised lighting consoles manufactured by ADB. The desks use ISIS software running on an external PC-based processing unit which allows advanced networking possibilities.
ADB website

The property of some materials that can store light energy and glow in the dark.

A lamp used by photographers which gives a bright white light. Because it has a thin filament, it gives a good flash effect (eg lightning), but has a relatively short life, so should not be left on for any length of time.

Resistance dimmer board heavily used in the USA before computerised lighting came along in the 1970s. 
Heavy construction, and ran on DC current. 

1) Device which, when attached to an acoustic musical instrument, converts sound vibrations into an electrical signal.
2) A way of describing the directional sensitivity of a microphone. An Omnidirectional microphone has equal pick-up from all around, a Cardoid microphone is more sensitive from the front, a Super-Cardoid or Hypercardoid has very strong directionality from the front. A figure-of eight microphone picks up front and rear, but rejects sound from the sides.
3) The action of turning a followspot on a performer. (e.g. 'that was a good pick-up', 'your next pick-up is downstage left'). A BLIND PICKUP is on a moving performer and requires good hand-eye co-ordination. A SET PICKUP is on a specific area, is preset, and is made on a cue from the stage manager. A SIGHT PICKUP is made visually by the operator to a preset position.

A handheld digital projector, usually battery-powered. Many different models are available, with a wide range of brightness levels (measured in Lumens). Also known as mini projector, mini beamer, pocket projector.

(USA) A short wire used to extend an existing electrical circuit or to add an additional link to an existing circuit. 
Term not recognised in the UK. Work on electrical systems should only be carried out by qualified electricians. 




Pinspot 1) A lantern focused very tightly on a small area (eg an actors head) - a pin spot.
2) A luminaire used widely in disco installations, consisting of a low voltage (6V) Par 36 lamp (lamp code is 4515) with a very narrow beam in a metal case with built in transformer.
Pinspots are ideal for lighting MIRRORBALLs.

Lanterns hung at the very ends of lighting bars - used for crosslight and very common in dance or musical theatre.

The ability with some advanced lighting desks and LED lighting fixtures to make each LED component within the fixture respond to a video signal. With a large number of LED fixtures, incredible fluid effects are possible that would take days to program manually.

A scale drawing showing a piece of scenery, the whole set, lighting layout etc from above.
Lighting plans are usually drawn onto the theatre's GROUNDPLAN, which shows the whole stage and (at least) the front row of audience, and has the scenic design drawn onto it. The groundplan usually includes the permanent flying bars in the venue, often drawn down the side of the plan on both sides of the stage. 
A view from the side of the set (or a piece of scenery) is known as an SECTION, usually a slice through the centre line of the stag, showing the stage floor, vertical heights of scenery, lighting bar (and flown scenery) positions, and also lighting positions in the auditorium, and is used for checking lighting angles etc. 
An ELEVATION is a similar vertical slice through the venue, or individual scenic elements, and can be drawn from the front, back or side, depending on where the important detail is.
A FLOOR PLAN shows the layout of furniture / scenery for a particular show, or for an individual scene. It shows the stage area only. 
A RENDERING shows how the audience will see the set, from the auditorium, and is often in full-colour. A different rendering may be done for each scenic layout used in the show. 

Professional Lighting and Sound Association (UK).
See ESTA for the American equivalent.
PLASA website

The part of a computerised lighting control desk which enables the operator to recall cues from the electronic memory.

1) List of preparations and actions required of technical crews during the performance (eg Sound Plot = list of sound cues and levels in running order.) In the US, the term plot refers to a plan. (eg Light Plot = scale plan showing lighting instruments). See also RUNNING PLOT, STATE PLOT.
2) Session during which lighting states are created or checked with the director, on stage, with furniture and stand-in actors. This is also the name for the session during which sound levels are set (but this should not happen at the same time as the lighting plot!). 
3) The basic story thread running through a performance / play which gives the reason for the character's actions.

Time during which the plot for each department is prepared (eg Lighting Plotting session). Also known as The Plot. 
See also PLOT. 

A power or signal connector with a pin or pins which is used to make a connection from a power or signal source (the socket) to a device or another connector. 
Plugs are not used as a source of power, because of the risk of electrocution by touching the fully exposed pin connections. 
Sockets, where the connection is shielded, are used as the source. 

A cue inserted during / after plotting between two existing cues. (eg 8.5 is inserted between cues 8 and 9). Most computer lighting desks have the ability to either insert an additional cue in a sequence, or to link to another cue out of the sequence, and then link back again. Inserting cues into a plotted sequence on a manual lighting desk is more awkward, because it is a running plot (where only the changes between cues are noted down). Stage Management may prefer to call 8A instead of 8.5, but this is down to personal preference.
Sound cues which relate to an already-running cue within a sequence should have lettered cues (e.g. 8A is a fade up of Cue 8 and 8B is the fade out).

A mechanical means whereby pan (horizontal rotation), tilt (up and down) and focus of a lantern may be adjusted by a pole from floor level. Commonly used in TV & Film studios where fast resetting of positions is necessary.

The power factor of an electrical system is the relationship between the power that should be used by the system, and the power that is actually being used. Stage lighting dimming systems, and newer innovations such as LED and fluorescent lighting can have very low power factors, which can result in very inefficient use of the electrical supply.
Large lighting installations should use power factor correction equipment to increase the power factor.
Power Factor information

Powercon Connector range (Neutrik) Power connector rated at 20 Amps with the same body type as the SPEAKON speaker connector. Manufactured by Neutrik. Used extensively on lighting patch panels (at least in the UK) due to its smaller physical size and lower cost than the standard 15A socket.
The blue connector is for power inlet, the grey connector is power outlet. The types are not interchangable, and cannot be plugged into Speakon sockets.
NB: The powerCON connector is not designed to be connected under load conditions, so should only be connected / disconnected with the power OFF.
Neutrik Powercon page

Any object which appears to do onstage the same job it would do in life, or any working apparatus (eg light switch or tap).
A window within the set which has to open is a practical window.
Light fittings which have to light up on the set are called Practicals, and if they're suspended from the rig, they're Hanging Practicals. 

(Lighting) Rigging the stage lighting equipment required for a show in advance of the show arriving at the venue. 

A section of the lighting rig which has been set up in advance of arriving at the theatre, or that remains rigged and tours into different venues as a complete unit. An example is a Six Lamp Bar - this is a bar rigged with 6 Par64 lanterns for rock and roll concerts, which has a single multi-way Socapex or Lectriflex connector which plugs it into the dimming system. 
Larger tours now have trusses pre-rigged with moving lights straight from the truck. 

A type of lamp base which ensures that the filament is correctly lined up relative to the reflector and lens.

Smoother lighting builds from zero are achieved when a tungsten lamp filament has been warmed (at approx 15%) in the previous state.
Preheating lamps MAY prolong the life of the lamp by reducing the thermal 'shock' of going to 100% instantly. It's good practice to preheat lamps where possible, and some computerised lighting desks provide this function at the push of a button.
This is not required for LED or discharge sources.
See also RIG CHECK.

Strand Prelude 16/30 Profile (650W) (Trade Name) Range of 500W/650W lanterns produced by Rank Strand (now Strand Lighting) in the UK.
Strand Lighting website
Strand Archive

1) Anything in position before the beginning of a scene or act (eg Props placed on stage before the performance, lighting state on stage as the audience are entering.)
2) The process of putting any part of the production into its' starting position / setting. A Preset Checklist is used by stage management and all other technical teams, to ensure that everything is correctly set to start the show.  
3) An independently controllable section of a manual lighting board which allows the setting up of a lighting state before it is needed. Each preset has a master fader which selects the maximum level of dimmers controlled by that preset. A control desk with two presets is sometimes known as a '2 scene preset' desk. 

1) A performance (or series of performances) before the 'official' opening night. Previews are used to run the show with an audience before the press are allowed in to review the show. This allows technical problems to be ironed out while ensuring the cast and creative team get audience feedback. Tickets are sold at reduced price and help to spread word of mouth interest in the show.
2) A function on some memory lighting control desks with video mimics. Preview enables the operator to see the levels of dimmers and other information in a lighting state other than that on stage.

Computerised tools which enable design teams to show directors and other members of the production team how lighting, scenery or scenic automation will look before the set is even built. See WYSIWYG.

The primary additive colours of light are red, green and blue, and the subtractive colours are cyan, magenta and yellow.
The primary colours of paint are different - they're cyan, magenta and yellow (although you may have been taught they're red, blue and yellow). 

A multi-faceted lens that splits the light beam in a moving light (or other effects light) into multiple beams. Particular effective when used with gobos. 

Table in the auditorium at which director/designer etc sit during rehearsals (especially technical rehearsals). Usually has its own lighting and communications facilities. 
For small venues the desk is used by the lighting designer and her/his team so that they can see the lighting from the audiences' point of view. The lighting control desk may be moved to the production desk, or the desk and programmer may remain in the control room, and have a remote interface on the production desk, which may have a display screen showing the cue list etc, which the designer can configure. 
Larger shows (including Broadway and West End) will often remove large sections of audience seating in the stalls and install a number of production desks for all technical areas including lighting, projection, sound, scenic automation etc. 

Member of the electrics team in a theatre (or contracted by a production) who is responsible for the technical preparation of the lighting rig. The interpretation of this role is varied depending on the size of the production / venue. It may include taking the lighting plan and generating paperwork such as lists of equipment, colour gel requirements, circuit hookups (which dimmer connects to which socket in the rig / which DMX channel) etc. They are also likely to be responsible for ordering / preparing additional equipment for the rig (e.g. boom stands), preparing the rig for focussing etc.
Also known as Prod LX. 

A gathering of key production staff during the months leading up to a performance or event. The aim of the meeting is to come to an agreement about any questions raised during rehearsals or the construction phase, to deal with any budget problems, confirm detailed schedules and to keep the process moving forward successfully. Decisions should be written down and circulated to those present and anyone that couldn't make the meeting. 

Strand Prelude 16/30 Profile (650W) 1) A type of lantern with at least one plano-convex lens which projects the outline of any chosen shape placed in its gate, sometimes with a variable degree of hardness/softness. Profiles include four beam-shaping metal shutters, a gate to take an iris or gobo and an adjustment to make the beam smooth and even ('flat') or hot in the centre ('peaky'). See Bifocal Spot, Zoom Profile.
2) Shaped piece of scenery added to the edge of a flat instead of a straight edge. Also known as a cutout.
3) Blocking notation for an actor that is facing directly offstage. Right Profile is facing off stage right, Left Profile is facing off stage left. 
Types of Lantern
Blocking Notation

1) Slides are used to project still archive images or textures. Libraries of slides contain images for every occasion. Kodak Carousel projectors are the industry standard, and some types can be linked to a controller to perform complex dissolves and fades from one projector to another. More powerful projectors are available using very intense discharge sources and large format glass slides to produce a massive image.
2) Lighting effects : Moving cloud / rain / fire effects can be achieved using a powerful lantern known as an effects projector with a motorised glass disc painted with the required effect. An objective lens is required in front of the disc to focus the image. See Effects.
3) Gobos : See GOBO.
4) Film : 35mm film projection is common in many theatres as a device for keeping the building open to the public when productions are in preparation. 16mm film projection is used in smaller venues. Film projection can, of course, also be integrated into a performance.
5) Data: Data or Video projection is now being used to bring video and computer images to the large screen. Data projectors are considerably cheaper and more versatile than other methods, and the quality is improving all of the time. Images can be front projected or back/rear projected depending on the amount of space and the effect required. For example, if actors are required to walk in front of the screen and not have the image appearing on them, back projection is the only answer.
6) Front Projection: The projector(s) are in front of the projection surface or screen, between the screen and the audience. This results in a bright image, but means that actors standing directly in front of the screen may cast a shadow on the screen (and have projection on their faces). 
7) Rear Projection / Back Projection: The projector is behind the projection surface. This means the projection image will be reversed from the point of view of the audience (all data projectors have a setting to flip or mirror the image). A standard white cloth or sheet can be used, but the image will be dimmer than it would be from the front, and (most importantly) the projector lens will be visible as a bright hot spot in the projection. To avoid this, a custom-made back projection screen should be used. Companies such as Rosco sell back projection (BP) material (a translucent plastic) which results in a very bright and clear image, and which prevents the visibility of a projection hot spot. The BP material can be stapled to a frame to form a screen of the exact size needed for the event. 


Power Supply Unit.

A simple way to lay out a complex lighting rig, either on paper or on a magic sheet in lighting software. Large shapes / blobs are used to depict areas of the stage or particular rig functions, so they can be easily selected or entered into the lighting software. 

The amount of electrical power required by a touring show in a venue.

A lighting desk setup for a visiting designer/operator to quickly 'busk' the lighting as required for a band / event, without any preparation time. The punt page may contain colour washes, effects etc as appropriate to the venue, event and stage type, ready for the visiting LD to use.

Plastic insulating tape used for taping cables to bars and for securing coiled cables. Neater and cheaper than Gaffa tape. Also known as LX tape.

2) Short for Pyrotenax, a brand name (UK) of Mineral Insulated Cable.

(often shortened to just 'Pyro') Chemical explosive or flammable firework effects with a manual detonation. Usually electrically fired with special designed fail-safe equipment.
There are many different variations of pyrotechnic effects available. The categories are as follows:
Theatrical Flash - a flash and a cloud of smoke
Maroon: produces a very loud bang. Must only be detonated inside a bomb tank covered with a protective mesh.
Gerb: version of the Roman Candle firework, throwing a shower of sparks into the air. Possibly named from the French 'Gerbe' meaning a sheaf of wheat, due to it's shape.
All pyrotechnics should be used with close reference to local licensing laws, and the manufacturers instructions. Professional advice should be sought before the first use of effects.
Some territories only permit licenced pyrotechnicians to use these devices.
The word originates from the Greek for fire, pyr

Quadbox Gearwrench Quad Spanner A double-ended, double-sided ratchet spanner designed to fulfill all of the requirements for a stage rigger.
In the UK, Quad spanners typically include 13mm, 17mm, 19mm, 21mm sockets, which fit M8, M10, M12 bolts and scaffold clips. 
A popular range in the US is made by Quadbox. 
See also Podger.

Strand Quartet PC (500W) 1) A group of 4 performers in a musical. 
2) A range of 650W lanterns made by Strand Lighting in the UK. 
Strand Quartet


(Manufacturer) Range of TV/Film lanterns marketed by Strand Lighting.
Quartzcolor products at Strand Lighting archive

R & V
(Manufacturer) Reiche & Vogel. German manufacturers of low voltage beamlight. Now sometimes used to describe any beamlight.
Reiche & Vogel website

1) A cabinet of standard width (19') into which various components can be bolted. Racks are ideal for touring equipment, are neat, and they allow easy access to the rear and front panels.
2) See Dimmer Rack.

System whereby battery-powered practicals / props on stage can be controllable from offstage with no connecting leads.

Illuminated music stand (named after manufacturer).
R.A.T. website

Named after it's inventor, Australian rock lighting tech Ray Hawins, the Raylight as designed to use A1233 500W lamp and a custom reflector, instead of the PAR64 lamp. It produced a narrow pure white beam. (Definition from Phil Dunesky)

Residual Current Device. Protects the user against short circuit (earth faults) and earth leakage caused by damaged cable or faulty equipment. A RCBO is a combined MCB and RCD, protecting against earth leakage/short circuit and overload. Known as a GFI (Ground Fault Interruptor) in the USA.

Remote Device Management. New lighting control and configuration protocol (officially ANSI E1.20 standard) currently under development at ESTA, which allows two-way communication over standard DMX512 cable, so that settings of a variety of RDM-compatible devices can be confutured remotely.

To change the lighting rig after the last performance of one show to the positions for the next show.


Musical terminology for a sung dialogue passage, in the rhythm of ordinary speech, during an opera, operetta or oratorio. Often shortened to RECIT.

800W open-faced adjustable flood lamp used in film / TV lighting. So-called because of it's red paint finish. See also BLONDE.

Highly polished metallic mirror used to direct light beam from a lamp towards the lens at the front of a lantern.

When a show is touring, a Relighter is used to reproduce the lighting design in each venue.
The original lighting designer may be present at the second venue on the tour, to check the work of the relighter.
Paperwork is produced by the original designer to enable the relighter to reproduce the design easily in venues of differing sizes.

A command used on Strand Lighting memory control desks which is comparable to the SOLO function on other desks. For example, entering CH 5 REM.DIM will put channel 5 at full and will put everything else at zero.

A lighting rig that combines the requirements of a number of different productions that are running 'in rep' in the venue. There will also be a different set, collection of props, costumes etc for each show, all of which must fit into the storage available in the theatre. Running a rep season is less popular nowadays, but was a staple of many UK regional theatres until the 2000s.

A now obsolete method of dimming which decreases the current available to the load by introducing a variable resistance between supply and load. The excess current is converted into heat. Based around a rheostat.

1) The point during a drama when the plotline reaches a conclusion, and conflict is resolved.
2) A measure of the quality of a video display / projection. Measured in the number of pixels width x height. 
3) The quality of a sound sample is measured by the sample rate (e.g. 44.1kHz is CD quality sample rate) and the resolution (either 8 bit or 16 bit normally).

A cue to resume or return to any previous state, setting or function. (e.g. 'at the end of the dance number we restore to a warm general cover').
Submitted by Bert Morris.

A modification that can be made to an existing piece of equipment after purchase to bring it up to date.

A method for entering commands to a control system (e.g. a lighting desk) which avoids the need for an 'Enter' key, by issuing the command at the end of the command sequence. 
This unintuitive method was very efficient once the programmer had learned it, but it's a very steep learning curve.
The method is used on AVAB consoles such as the Viking range (late 1980s) and on the ETC Cobalt. 
AVAB Reverse Polish (1989)
AVAB Viking

Remote Focus Unit. Name used by ETC for a remote control for the lighting desk. Same as RIGGERS CONTROL.

Part of an electrical circuit for varying the electrical current going to a load (e.g. an incandescent light bulb). A length of reistance wire is wound around an insulator which is connected at one end to the supply. A movable contact which passes along the windings is connected to the load, with the result that when the contact is at the end of the wire nearer the supply, the maximum current is passed. As the contact is moved down the windings, the electrical current reduces, resulting in dimming of the lamp / load. 

1) The construction or arrangement of lighting equipment for a particular production.(noun)
2) Installing lighting, sound equipment and scenery etc for a particular show.(verb)

(also known as LAMP CHECK) The process of checking all lanterns in the rig are working correctly prior to each performance. Should be done daily in sufficient time to change a lamp if necessary.
Most venues do not have the electrical capacity to run all lanterns at full for a rig check, so a level of 25% is normally used.
N.B. this is NOT the same as preheating - a rig check happens before each performance and involves the whole rig, and preheating involves individual lanterns/dimmers and happens before a cue in which that lantern appears.

A remote control for a lighting desk which enables dimmer channels to be called up from the stage when rigging or focusing. Usually battery powered, sometimes with infra-red (cordless) control. A Designers Control allows whole memories to be called up and/or played back, as well as individual dimmers.

1) (UK) Standard way of wiring socket outlets around a room in the UK. The socket outlets are wired in a ring, with a 32A circuit breaker / fuse protecting the ring. Each socket outlet is rated at 13 Amps, but all of the sockets on the ring have a maximum load rating of 32 Amps. Care should be taken to understand how many rings exist in a given room, to ensure the circuit breaker does not trip during an event/performance. Professional venues have larger capacity power outlets (e.g. 32A or 63A, or even 125A outlets, which production power distribution systems can plug into). 
2) (Film/TV) A system of monitors relaying footage from the studio around dressing rooms and production offices

Root Mean Square. A measurement of the effective voltage of an alternating current waveform. 
RMS Voltage

Lighting control desk designed for rock concerts, the main feature of which is the ability to group a set of dimmers under the control of a series of flash buttons, enabling the operator to 'play the lights' in time to the music. These desks usually have a very good lighting effects capability.

(Manufacturer) USA based manufacturer of lighting gels and scenic products. See COLOUR FILTER.
Rosco Labs website

When rigging a lighting bar (or an individual lantern) it's helpful to have an awareness of where it will be pointing during the show. When you attach the safety wire and plug the lantern into the power supply, if it isn't focussed roughly in the right direction (e.g. is it a downlighter, or is it backlighting or sidelighting), there's a danger that the cable will restrict movement when the lantern is focussed more accurately during the focus session, wasting time while the cable or safety wire is released. 
Doing a rough focus will also ensure that accessories such as barndoors do not physically obstruct the light from nearby lanterns. 

A circular lighting filter either made of plastic (known as a GEL) or of glass for more permanent applications or architectural installations.

Computer networking device which connects different networks together. Common uses in theatre are to connect technical networks to the internet, or to create wifi networks for technical purposes. Network cabling can connect lighting desks to dimmers and to additional interfaces to enable wireless control or computer-based control of systems. In sound, mixing desks and remote input/output interfaces can be connected via network cable, saving vast amounts of time connecting multicore audio cables, and again enabling wireless remote control of various systems. 

US term for the blue working lights used backstage during a performance.

A plot sheet giving details of the changes between cues, as distinct from a state plot which gives the whole state of the system at any time. For example, a lighting plot on a manual board is normally a running plot. It is difficult to start a running plot half way through; often the operator has to go back to the beginning and work through until the required point is reached. However, it contains the minimum information necessary to perform the cues, and is therefore more efficient on a manual lighting desk or complex sound setup.
Also used by the stage management team to keep track of prop moves and changes during the show. A preset sheet contains the status of everything at the start of the show, then the running sheet / running plot lists everything that has to happen during the show, in order.

Streaming Advanced Control Network, or Streaming ACN.
Control protocol developed by ESTA to use a standard computer network to send a number of DMX universes between equipment. Similar to ArtNET.

Lighting control software originally manufactured by AVAB Scandinavia. Safari software is now maintained by ETC.
Safari is also the web browser installed on Apple computers and devices.
AVAB website
ETC website

Safety Bond, rated at 35kg (from Chain or wire fixed around lantern and lighting bar or boom to prevent danger in the event of failure of the primary support (eg Hook Clamp). A requirement of most licensing authorities in the UK. 
As a standard safety chain does not have a rated loading, current recommendations in the UK is to use an approved (and rated) safety wire (also known as a safety bond) as a secondary suspension. 
Although hook clamps (in the UK) that support lanterns do not fail, they are subject to a number of human failings including not doing the clamp up sufficiently or not tightening the bolt at the base of the hook clamp that connects to the lantern. However, the highest risk is due to a flown lantern being struck by a piece of scenery or another lantern as it flies past. 

Safety Chain, unrated An old form of secondary suspension used on rigged equipment. 
Because the chain cannot be rated to carry a specific load, safety chains should no longer be used in this application, but should be replaced by rated safety bonds. 

Adrian Samoiloff was a Russian artist / lighting designer / scenographer, who used complementary lighting colours to transform scenes and costumes. His shows were run at the London Hippodrome in 1921, and were the talk of London, and later New York. 
The Samoiloff Effect uses complementary coloured lighting to make scenery / costumes look different under different states. 
Adrian Samoiloff at

Network operating system integrating standard communications protocols with a multitude of industry and manufacturer-specific control protocols.
Sand Network Systems website

The amount of colour in a lighting state, paint treatment or costume design.
The term is usually linked to Hue, which is the colour of a light, costume or piece of scenery (etc.). 
A de-saturated treatment has less colour than before. 

An arrangement of lanterns in which to maximum number of spotlights is placed in every possible position.

(US especially) To extinguish a particular lighting instrument (e.g. 'Save 14'). The instrument's lamp (and its colour filter) are thus saved for another occasion. Used when setting up lighting states.
Submitted by Peter Neilson

1) System of pipes, clamps and boards which is used in the construction industry to form levels to improve access to high buildings either during construction or maintenance. Shortened to Scaff. 
2) The same system can be used for set construction, with adequate supervision by experienced / qualified persons. 
3) Scaff tubes / pipes are 48mm in diameter and are used as vertical legs on platform systems by various manufacturers including Steeldeck, Metrodeck, Prolyte Staging etc. Originally made of steel, scaff tubes are usually now made from aluminium which is a much lighter weight and therefore easier to work with and safer from a manual handling point of view.
4) Horizontal bars to rig lighting equipment from are made from scaffold tubes (48mm diameter). 

General name for a moving mirror lantern, especially those used in discos, rather than the more flexible units used in theatre.

1) A pre-programmed lighting state which can be faded in and out during a one night show when there's no time for plotting.
2) A subdivision of a play. See also ACT. Scene is often shortened to 'Sc', so Sc1 refers to Scene One. 

A diagram showing the layout of a complex set of equipment, using simplified graphics / symbols to depict the equipment. 
A lighting plot is a schematic. 

A scissor lift is a type of aerial work platform (AWP), also known as an aerial device, elevating work platform (EWP), or mobile elevating work platform (MEWP). The AWP is a mechanical device used to provide temporary access for people or equipment to inaccessible areas, usually at height. The MEWP can usually be driven around the work area by the operator at height to provide safe access to a wide area, on a flat floor. Scissor lifts have also been used in scenic automation to provide a moveable platform, often built onto a moving base. The scissor lift is used because it is a self-contained device which requires no construction for it to operate within, and which does not extend beyond the horizontal dimensions of the platform.
The mechanism to achieve the vertical lift is the use of linked, folding supports in a criss-cross X pattern, known as a pantograph (or scissor mechanism). The upward motion is achieved by the application of pressure to the outside of the lowest set of supports, elongating the crossing pattern, and propelling the work platform vertically. The platform may also have an extending bridge section to allow closer access to the work area, because of the inherent limits of vertical-only movement.
The contraction of the scissor action can be hydraulic, pneumatic or mechanical (via a leadscrew or rack and pinion system). Depending on the power system employed on the lift, it may require no power to enter descent mode, but rather a simple release of hydraulic or pneumatic pressure. This is the main reason that these methods of powering the lifts are preferred, as it allows a fail-safe option of returning the platform to the ground by release of a manual valve.

A wall-mounted light fixture, where the light is directed upwards. Also refers to a wall-mounted flaming torch.

A special type of floodlight consisting of a lamp mounted in a large ellipsoidal reflector. The body of the instrument is usually circular which means a soft edged circular beam is produced. A standard FLOOD has a rectangular body.

Silicon Controlled Rectifier. See THYRISTOR.

Many types of projection screen are available. Some are multi-purpose, some only for front projection, some only for back projection. If a screen is not self-supporting, it often has eyelets around the outside edge which are used to 'lace' the screen onto a larger frame.

DIsplay window on a lighting, sound or automation control desk which enables the user to add a description of the function of that channel. Can be entered as text, or a hand-drawn image or text. This enables graphical characters (e.g. Chinese) to be used, or other symbols. 
On older analogue systems, the channel function was written on a piece of white PVC tape that was stuck on the control desk. Some systems had a white plastic strip on which chinagraph pencils (wax) could be used. 

1) A coarse gauze
2) A fine metal mesh used to reduce the intensity of light from TV lanterns without affecting colour temperature.
3) Plastic gauze-like material used to line Heras fencing at festivals and other events to act as a partial sight-screen, and also to make the fencing tone in with surroundings.
See also Lighting With A Gauze / Scrim

Rainbow Colour Scroller (from GearSourceEurope) See COLOUR CHANGER.

Separately powered lighting system for use throughout the building in the event of failure of the primary system. Usually battery powered. Maintained lighting is on all the time, regardless of changes in the stage lighting, and is battery backed-up.
Non-maintained systems only light in the event of power failure or an alarm condition.
Secondary lighting systems should be regularly checked by an electrician to ensure they operate correctly.

(Manufacturer) New Zealand-based manufacturer of theatre lanterns.
Selecon website

Colour Changers at the Backstage Heritage Collection

The study of signs - many conventions in lighting design rely on signs (blue must be night-time, red is evil etc.)
Semiotics for Beginners

An adaptor consisting of a plug and two sockets wired in series. Enables two identical 110 Volt loads to be safely run from a 240 Volt supply (UK).

1) Artistic lighting design can (sometimes) be about what is not lit as much as what is. Light and Shade together make up the overall picture.
2) A lampshade is positioned around a light fitting to direct the light as desired and to improve its' appearance.
3) Actors strive for a variation of tone and emotion -  the terms light and shade are sometimes used to describe the tonal variety.

A dark area on stage resulting from a person, piece of scenery or other object blocking the rays from a light source. 
Shadows in theatre lighting may be highly desirable, or unwanted, depending on the situation. 
In the natural world, bright sunlight produces shadows, and the length of the shadow defines the time of day. A cloudy day results in hazy or no shadows. Indoor lighting produces a shadow from each light source. It follows that naturalistic lighting requires either a single shadow (to replicate sunlight) or no shadows for outdoor scenes, and a shadow per practical light source for indoor scenes. It is very difficult to achieve this ideal, but a bright backlight and a dimmed front light can help to remove/reduce shadows from the front light and create a single one from the backlight.

The common Australian term for AJ's, c-wrenches, spanners etc.

The lowest lantern on a lighting boom. Named because of the proximity of sharp parts of the lantern to the flesh of the lower leg. This especially applies to standard dance lighting, when the lanterns are positioned at optimum height to light dancers on the stage floor. When the boom is lighting scenic items or large groups, the lanterns may be higher up the boom and the term will no longer apply.
Also known as Shin Buster. The other lanterns on the boom are known as MIDS and HEADS.

Normally refers to a Short-Nose Parcan - a lighting instrument that uses a normal size PAR lamp, but has been shortened to either make it less obtrusive, or to get a wider beam angle.

Shutter from Strand Lighting Prelude 16/30 Profile lantern Part of a profile lantern. Metal blade which can be used to shape the edge of the beam. Shutters (normally four) are located in the gate at the centre of the lantern. Similar in effect to barndoors on a Fresnel or PC lantern, but a lot more flexible.
The position of a shutter in the light beam is known as the shutter cut

City Theatrical Safer Sidearm US equivalent to a UK Boom Arm. Used to mount lanterns onto vertical booms. 
City Theatrical Safer Sidearm

Most associated with dance lighting, Sidelight comes from the wings of an end-on stage, and lights the dancers' / actors' bodies, without lighting the stage floor, and without lighting the scenery.
This type of light has a sculpting effect on the bodies, and really separates them from the scenery / backdrop / cyclorama, and reduces distracting shadows on the stage floor.

A pair of metal rings attached to the side or top of a followspot which enables the operator to accurately line up the beam (by looking down the length of the followspot through the rings) before turning it on. See GHOSTING.

1) To light the cyclorama or a piece of upstage set in such a way that the actors are cast into shadow. Can be a very dramatic effect.
2) (Trade Name) A range of 2000W lanterns manufactured by CCT in the UK.
3) The outline of a costume is called the silhouette.
CCT Silhouette in the Backstage Heritage Collection

A special type of diffusion frost filter which stretches the light in one direction. Especially useful for lighting large cycloramas with a limited number of lanterns, or for lighting an elongated object (eg a staircase) with one lantern.

A substitute for a real flame, consisting of flame-shaped pieces of light-coloured silk, with an orange/red light underneath, and blown by a fan pointing upwards.  The airflow keeps the silk upright, with a random movement which from a distance reads as a flame.

(Trade Name) Manual/memory lighting control desk previously manufactured by Zero 88 in the UK. Available as Sirius 24 (24 channels) or Sirius 48. Desks can be linked together.
Zero 88 website

"Meatrack" / Transporter Trolley (Doughty Engineering) An internally-wired lighting bar, designed for touring, with six socket outlets terminated in a multi-way connector (e.g. SOCAPEX or LECTRIFLEX). Often pre-rigged with lanterns (eg Parcans). Stored in Meatracks. A bar pre-rigged with Parcans is sometimes known as a PAR BAR.

35mm slides on a light table (Dusan (canstockphoto)) See PROJECTION.


Smoke Detector (Photo-Electric sensor) Many theatre buildings have complex fire alarm systems installed. Some theatre spaces have smoke detectors in them, which trigger a fire alarm when the space fills with smoke. The use of SMOKE MACHINES in these spaces can (and does) result in expensive call-outs of the fire department and evacuated auditoria.
There are special heat-sensitive detectors called RATE OF RISE detectors which trigger a fire alarm when the temperature rises faster than it should normally. Properly calibrated (and regularly tested) these can be as effective than the smoke detectors (which work by 'seeing' smoke particles in the air). If it's not possible to get Rate of Rise detectors installed in your theatre space instead of smoke detectors, you may be able (subject to local building regulations and local fire department advice) to isolate the smoke detectors for the duration of the performance when you use smoke effects. Properly designed alarm systems incorporate timed isolation, so that smoke detectors are only off for a specific period, and automatically come on after that period.

A Smoke Machine or Fogger is an electrically powered unit which produces clouds of white non-toxic fog (available in different flavours/smells) by the vaporisation of mineral oil. It is specially designed for theatre & film use.
A Haze machine, Hazer or Diffusion Fogger is used to produce an atmospheric haze, rather than clouds of smoke, and is used by many lighting designers to reveal airborne light beams.
The first smoke machines came onto the market in the late 1970s.
It's essential to know whether your venue uses SMOKE DETECTORS on the fire alarm system. See that entry for more information.
Fog / Smoke / Haze On Stage

A lighting or sound cue with no fade time - the cue happens instantly.
This can be acheived on a computerised lighting desk by using a fade time of zero seconds.

Lighting: A sudden cut to blackout (often abbreviated to SBO). A blackout with a fade time of zero seconds. 

Snapper 15A Adaptor known as a Grelco (UK) See GRELCO.

Function on ETC lighting desks which allows you to remove a channel from a 'live' lighting state at a preset speed.
(e.g. SNEAK 1 ENTER will fade channel 1 out of the current lighting state).



19-pin Socapex plug and socket (from Wikipedia, by Hugovanmeijeren) A multipin connector which can carry a series of lighting or sound circuits. Very robust and designed for touring. Available in 19 pin (6 circuits) and 37 pin (12 circuits) configurations. Sometimes shortened to SOCA. See also LECTRIFLEX.

A power or signal connection point where a plug can be inserted to make a connection from the source of power. Sockets can be used as signal outputs or inputs, and are usually used as power outputs, due to the shielded connections, making it impossible to touch the live connections with fingers. 
Sockets are often wall or panel mounted, while plugs are used to connect portable equipment. 
There are exceptions of course - powercon connections which are panel mounted can be either power inputs OR outputs, and are differently colour coded to make it clear which is which, and the connectors are designed so they cannot be used incorrectly. 

Short for Software Key. A button on a lighting or sound desk whose function changes according to your last action. The function of the soft key is often shown on an adjacent display panel. The keys are often numbered rather than being labelled (e.g. on the ETC Express and Ion range of lighting desks, the soft keys are numbered S1 to S8).

Asymmetric flood light used as a fill light in TV studios to eliminate shadows and balance the key light.


1) On a sound desk, the solo button on each input channel silences all other inputs so that channel alone can be heard. Dangerous to use during a show, but can be useful for fault-finding or testing equipment.
2) On a lighting desk, SOLO mode kills all other channels except the single dimmer you're working with. Again, can be useful for identifying a channel in a large rig, but can be dangerous during a show. Some desks allow you to assign flash buttons to SOLO mode which will turn off all channels except those loaded into that flash button or submaster. This can be used for a quick lightning effect (but it's a bit tacky). On Strand Lighting memory desks, the solo function is called REMAINDER DIM (or REM DIM).

An audiovisual entertainment often based on an historical theme (and often produced in a historically relevant location). A voice narration is often used and lighting / special effects set the mood and portray certain events in time with the narration. Often used to refer to a performance with no performer where the meaning is communicated solely with technical effects.

A facility which can link the effects panel on a lighting board to an audio input which detects treble, mid and bass beats, and can flash lights or trigger effects in time to those beats. First used when electronics allowed it cheaply in the late 1960's/

ETC Source Four profile (Trade Name) (Also known as S4) Range of lanterns manufacturer by ETC, and designed by David Cunningham. 
Source Four on the ETC website


An instrument within the lighting rig which is required for a specific moment or effect within the performance, and is not part of the general cover lighting. See GENERAL COVER.

The speed of light travelling through a vacuum is 186,282 miles per second.
A light year (the distance that light will travel in one year) is around 6 trillion miles. 

Adaptor to connect many lanterns to one multicore cable. Consists of multipin connector (typically Socapex or Lectriflex), short length of cable, then a number of sockets related to the number of circuits in the cable.

M10 Spigot to fit into a lighting stand (Doughty) An adaptor screwed onto the hanging bolt of an instrument to enable it to be used on an upright stand.

Unwanted light onstage.

Concentric rings attached to the front of a beamlight (eg Strand Pageant) to contain spill.


1) To reduce the beam size of a fresnel or pc lantern by moving the lamp further from the lens. (e.g. 'Could you spot that down a touch, please?'). See also FLOOD.
2) A profile spotlight (e.g. 'The third spot we need for the show is on the piano DSL')
3) A moving light that can project gobos and/or a beam with hard-focussed edges. (see also WASH)
Types of lantern

Chair for suspending followspot operator above a stage / auditorium. Normally rigged on a truss system. The operator gets to the seat up a wire rope ladder, and is strapped into the seat. They will normally wear a harness when getting to the chair for extra safety. The seat itself is an adapted car 'bucket' seat.

General term for any lantern with a lens system. See Fresnel, PC, Profile.
German: Theaterscheinwerfer

A connection box at the end of a lighting or sound multicore cable.

Member of the electrics staff whose responsibility it is to set or clear electrics equipment during scene changes. May also carry out colour changes on booms etc.
Sometimes abbreviated to SLX. 

End-On Stage Layout Plan ( Left/ Right as seen from the Actor's point of view on stage, when they are facing the auditorium. (ie Stage Left is the right side of the stage when looking from the auditorium.)
Stage Right = OP (Opposite Prompt) Abbreviated to SR. French: Cote Jardin, Netherlands: Toneel Links (translates to Stage Left!)
Stage Left = PS (Prompt Side) Abbreviated to SL. French: Cote Cour, Netherlands: Toneel Rechts (translates to Stage Right!).
NB: The Netherlands, Portugal and Germany use the opposite to the rest of Europe; i.e. Stage Left UK = Stage Right. The directions are seen from the director's and audience's perspective, NOT the actors. In Portugal Isquerda (left) is the equivalent of UK Stage Right and Direita (right) is the equivalent of UK Stage Left.

Stagecraft refers to any technical aspect of theatre production (and also sometimes refers to film / TV production). It includes working in technical areas such as lighting, sound, scenic construction, costume & prop construction, stage management and makeup. It usually does NOT refer to the creative / design aspects of those technical areas.

1) A warning given to technical staff by stage management that a cue is imminent. The member of the stage management team calling the cues will say "Standby Sound Cue 12". Technicians acknowledge by saying "Sound Standing By".
In the US, the word "Warning" replaces "Stand-by".
2) A member of the cast of a musical or play who understudies one (sometimes more) of the principal roles but is NOT also in the chorus. A standby often will not even be required to be at the venue at each performance unless they are called in to perform in the role for which they are an understudy.
Additional information submitted by Pierce Peter Brandt


(Trade Name) Range of 1000W/2000W lanterns produced by CCT in the UK.
CCT Lighting website
CCT Starlette on Backstage Heritage Collection

In lighting terms, a lighting 'picture' ; each lighting cue results in a different state (or a modified state).

A hand-written document consisting of the levels of all channels for each cue throughout the show, when using a manual lighting control board. The sheet is no longer required for modern computerised lighting systems. 


1) Refers to a steel blue / pale blue lighting gel. (Lee 117) (e.g. 'Use the Steel General Cover for the scene in the castle'). See also STRAW.
2) Many set construction now uses steel frames with timber cladding. Steel is stronger and lighter weight compared to timber of the same size.
3) Generic term used for a plain wire rope sling. Also used when referring to roof structural steel and individual steel beams or scaffold materials and so on.
Additional information submitted by Chris Higgs.

1) A control on some lighting effects boards which enables the operator to 'step' through a chase effect in time to music etc.
2) Each separate component of a lighting effect is called a step. A chase effect with four channels flashing on will have four steps.

Prolight Concepts - Global Truss Modular Rigging System - Moving light suspended from a stirrup connected to a modular extension Lighting rigging accessory which consists of a short piece of metal tube held by a U-shaped bracket which is designed to be suspended from above. The metal tube can be used to rig a lantern using a standard clamp. 

1) (Manufacturer) Maker of lanterns, lighting desks and dimmers in the UK and Worldwide.
2) The bundle of individual fibres or wires that make up one of the helical elements in a rope.
Strand Lighting website
Strand Archive

Refers to a pale yellow lighting gel. (e.g. "Use the Straw General Cover for the garden scene").
See also STEEL.

An even pattern of lines (or light/dark areas) visible in a light beam, caused by the design of the filament layout in the light source. 

1) A thin linear filament lamp similar to an Architectural, but having contacts at the ends of the lamp. Available clear or opaque.
2) (US) See BATTEN.

Device giving a fast series of very short intense light flashes which can have the effect of making action appear intermittent. Because strobe lighting can trigger an epileptic seizure, the use of a strobe must be communicated to the audience before the performance begins. Strobes should be synchronised so that they operate outside the dangerous frequency band 4 to 50 flashes per second. (i.e. a strobe should operate at less than 4 flashes per second, or more than 50 flashes per second). If the effect is momentary, this rule may be relaxed. Strobes must never be used in public areas where there are changes of level or steps.
Always seek the advice of the licensing authority if you are in any doubt about the safety of strobe effects.

Often shortened to SUBS.
Fader on a lighting desk which can have a lighting state recorded onto it for additional control, or to use when manually mixing lighting states for music concerts or one-off events.
Lighting desks normally have a series of submasters (12 or 24 are common) which can have states, cues or effects loaded onto them. Some desks can have submasters set to inhibit the main output (known as INHIBITIVE SUBMASTER. For example, the FOH lighting can be loaded onto a submaster which is then brought down as the house tabs are flown in between curtain calls to block light spill onto the tabs).
Multiple cues can be recorded onto some submasters through the use of pages.
A PILE-ON submaster can be used to add it's contents to the existing lighting state. Any number of pile-on submasters can be used in combination to modify a state.


Historic combination gas light array and ventilation system built into many theatres with gas lighting (pre-electricity). 

Super Trouper followspot (Strong International) (Trade name) Manufactured by Strong International - a range of high intensity followspots designed for large scale permanent installations or large touring shows. The Super Troupers use Xenon lamps and vary from 1600W - 2000W.
The Super Trouper is the best known of all stage lighting instruments outside of the industry due to Abba's song 'Super Trouper'.
Strong International website
Followspotting Tips and Tricks

Low voltage lighting batten used to create a light curtain. Named after Josef Svoboda, the Czech scenographer (1920 - 2002). The original Svoboda light batten is still manufactured by ADB. Josef Svoboda contacted ADB when he was looking for a manufacturer for his idea.
ADB website
Josef Svoboda in the Backstage Heritage Collection Archive
Svoboda Batten by ADB on the Backstage Heritage Collection website

3 or 4 , 500 or 1000 watt flood lamps mounted on a wooden skid,used as cyclorama bottom lighting or in between scenery groundrows. Probably derived from German theatre lighting company, Schwabe.

Gel Swatch Books - Rosco Supergel and Lee Filters A sample of fabric to demonstrate the material to use on a costume or set design, or a sample of lighting gel. A catalogue of all the gel colours made be a particular manufacturer is called a SWATCH BOOOK.
Rosco Supergel website

Safe Working Load.

Lighting Industry Forum code which identifies the (original) recommended usage of different lamp types. T coded lamps are for theatrical use, and have a colour temperature of 3000°K. See also CP, A1, P2, K.
Lamps List

1) Lighting focused onto the house tabs at the front of the stage to set a theatrical atmosphere before the show starts. May also involve a gobo with the show or company logo. Also known as TAB WARMERS.
2) Dressing the Tabs (or Dressing the Curtains) is the process of going along the curtain track and evening out the folds in the curtains so they are tidy and regular. 

Lighting focused onto the house tabs at the front of the stage to set a theatrical atmosphere before the show starts. May also involve a gobo with the show or company logo. Also known as TAB DRESSING.

1) Originally "tableaux curtains" which drew outwards and upwards, but now generally applied to any stage curtains including a vertically flying front curtain (house tabs) and especially a pair of horizontally moving curtains which overlap at the centre and move outwards from that centre.
If the tabs are flown, the instruction TABS IN is used to fly them in to cover the stage, and TABS OUT reveals the stage to the audience. If the tabs move horizontally, the tabs OPEN (to reveal the stage) and CLOSE (to cover it). 
[In French, tabs are Rideau. The main tabs or house tabs are Rideau d'avant-scène. In Spanish, the main tabs are Bambalinón.
A narrow stage curtain used for masking is Pendrillon
In Italian, tabs are Sipario.]
2) TABS was a journal published by Strand Electric between 1937 and 1986, about stage lighting and other equipment produced by the company. The Backstage Heritage Collection archive has a complete collection of TABS journals for you to read online.
TABS archive

Also known as BARE ENDS, TAILS refers to a cable or set of cables with a connector at only one end which is used for connecting a company's equipment directly to the mains supply in a venue. The connection should only be made by a qualified electrician with the power off!

Tallescope ( (Trade Name) A retractable alloy vertical ladder on an adjustable wheeled base. The platform at the top is just large enough to hold one person. Used for rigging lanterns, focusing etc. Collapsible enough to fit through a standard doorway. Outriggers are used to stabilise the tower from falling sideways. Two people are used to move and steady the tallescope. Sometimes known as a 'TALLEY'.
Aluminium Access Products - Tallescope Manufacturer and Service
Access Equipment

Tank Trap / Boom Base made by Doughty Engineering See BOOM BASE.

(also known as the TECH RUN, or just TECH). Usually the first time the show is rehearsed in the venue, with lighting, scenery and sound. Costumes are sometimes used where they may cause technical problems (eg Quick changes). Often a very lengthy process. Often abbreviated to the Tech.
A DRY TECH is without actors to rehearse the integration of lighting, scenic changes etc. It follows that a WET TECH is a full technical rehearsal with actors and all technical elements, although this term isn't used as often as DRY TECH.
A PAPER TECH is a session without the set or actors when the technical and design team talk through the show ensuring everything's going to work as planned. Stage Managers can use this session to ensure all is written correctly in the Prompt Book.


Abbreviated to TWG. A mesh above the stage comprised of steel wire under tension which can be safely walked on, and is transparent to light. 

Australian equivalent of the UK "PAT" Test - a regime for testing electrical equipment for safe operation and then logging the results.

An approach to traditional stage lighting taught by Stanley McCandless which uses two front lights (separated by 60 degrees horizontally) and one backlight to cover each lit area of the stage. The two front lights may be coloured differently (one 'warm' and one 'cold') so that a wide variety of lighting states can be created by blending the front lights in different intensities. 

An adaptor which enables three pieces of equipment to be connected to a single outlet or cable. Great care should be taken not to overload the circuit. See also TWOFER and GRELCO.

Distance between a light source (e.g. lantern or projector) and the actor or object being lit.

Figure used to calculate how large a projected image will be for a given distance to the screen (or vice versa).
For example, a throw ratio of 2.5 means that to achieve an image 4 feet across, the projector must be (4 x 2.5 = 10) 10 feet from the screen.
A projector 8 feet from the screen will result in an image (8 / 2.5 = 3.2) 3.2 feet across.
A short throw projector with a ratio of less than 1 will produce a larger image for a smaller throw.

Also known as an SCR (Silicon Controlled Rectifier). An electronic switch which will pass current when triggered until the current passing through it falls to zero. Essential component of stage lighting dimmers. See also IGBT, TRIAC.

1) Up and down (vertical) movement of a lantern, camera or moving light. The lantern is held in the wanted position by using a tilt knob, often on the right hand side of the lantern.The Tilt Knob needs to be undone to enable the lantern to be tilted up or down. The lantern should always be held in position when undoing the tilt knob, to prevent it dropping. See also PAN.
2) Feature on pinball machines which detects excessive movement of the case. Only related to theatre in connection with the musical 'Tommy'.

The facility on memory lighting boards for playing back timed fades at the touch of a button.

Rectangular area in the corner of a lighting plan (often bottom right) containing the name of the show, director, scenic and LX designer names, date of the plan, scale, and other copyright information.

Also known as HIGH HAT or SNOOT. Cylinder of metal inserted into colour runners on the front of a parcan, narrow-angle profile or other lantern to limit spill light, particularly when used in view of the audience. Sometimes additional SPILL RINGS are used at the front of the top hat, to further limit spill, and to reduce glare for the audience if they have a clear view of the lantern. 

A philosophy of operation on some lighting desks which memorises the operations required to carry out a cue, and NOT the entire state of each cue. For example, if a spotlight is added into Cue 2, it will remain on at that level through subsequent cues until a cue where all cues fade out, or a cue where that spotlight is specifically recorded at zero. This is very handy for adding in forgotten channels, or for removing errors. However, it can complicate things if you are plotting cues out of sequence. Most desks have a way of over-riding Tracking for a particular cue (known as Cue Only), or for the whole show you are working on. 
See the video below for further information. 
Tracking Video
Cue Only Video

An instant scene change, often effected by exploiting the varying transparency of gauze under different lighting conditions.
See also Lighting With A Gauze / Scrim

1) The movement of actors / scenery & change of lighting / sound between one scene and another.
2) Video: An effect applied to a change of shot / camera angle to make it anything other than a simple cut.

In the context of lighting gel, the transmission (usually expressed as a percentage) is the amount of the original light that is allowed to pass through the gel. A pale gel will have a high transmission value, and a heavily saturated deep coloured gel will have a low transmission value. The transmission lets you know how much light will be absorbed by the gel, and how much you'll end up with on stage.

Form of staging where the audience is on either side of the acting area.
Also known as ALLEY or AVENUE staging. 

(Triode Alternating Current switch) Electronic Semiconductor device which is an integral part of modern dimmers. When a current is applied to a triac, it starts conducting, and continues until the current passing through it falls to zero. Whereas a thyristor can only conduct half of the AC wave, a triac (as long as it's triggered at the appropriate point) will conduct both halves of the wave. 

A lightweight aluminium triangular cross-section truss manufactured by Optikinetics. 

1) US for DEAD on a flying piece. (e.g. 'The Out Trim on this piece is 14 feet from the deck')
2) Stage lighting dimmers can be adjusted ('trimmed') to change the point at which full level is achieved, and sometimes the point at which the light fades out, along the curve of the dimmer. This is known as the TOP SET. Older technology dimmers had to be trimmed each time the load on a particular dimmer changed, to enable the full range of dimming. 
3) (UK) The process of adjusting the supports for a piece of flown scenery to make it level relative to the stage floor. 

TRIPE (bundle)
Bunch of cables tied or taped together into a single unit.
Also known as a LOOM, or HOD (USA).

For lighting fault-finding / troubleshooting, please see the new page:
Lighting Fault-Finding:

More coming soon

1) Tough Rubber Sheath. Jargon for any Rubber-sheathed power cable. (e.g. "Go get me a 10m TRS" usually means "Please get me a 10m length of 15A power cable" (in the UK, at least)). 13A cable (or 5A cable) can also be TRS, so if in doubt, ask for clarification of the connector required, or check what it's for if you're not sure. 
2) Tip Ring Sleeve. The three contacts on a stereo jack audio connector.

Dado Trunking (TLC Electrical, UK) Metal or plastic wall-mounted enclosure for cables. Usually box shaped in cross-section.
Dado Trunking runs horizontally along walls at dado height, and enables socket outlets and various other services to be mounted in the system. 
Known in the USA as RACEWAY or WIREWAY.

U-shaped bracket between the hook clamp and the main body of a lighting instrument, enabling it to be tilted to any angle.

A framework of alloy bars and triangular cross-bracing (commonly around 50mm diameter) providing a rigid structure, particularly useful for hanging lights where no permanent facility is available. Very often box-shaped in cross section, so known as BOX TRUSS. This type of truss is useful for touring as lanterns / speakers etc can be hung inside the truss which protects them when loading and takes up less space in the truck.
You should only use truss from reputable manufacturers, and should check the manufacturers' website for instructions on how to use it, and what limitations it may have. 
Rigging a truss incorrectly can vastly reduce its' safe working load, and can result in damage to the truss,or a far more serious failure. Always seek advice from professionals, and do not attempt to rig equipment without proper advice or supervision. 
The cross-sectional shape of truss can either be FLAT (known as Ladder Truss), SQUARE (known as Box Truss) or TRIANGULAR (known as Tri-Truss). 

Large diameter tapered metal pin (also known as a bullet pin) which is used to hold pieces of truss together. The pin has a hole at the far end which is used with an R-Clip to prevent it coming out accidentally. Different sizes of truss pin are used for different manufacturers' truss. 


A standard tungsten filament lamp loses its brightness in its' lifetime. Tungsten Halogen lamps use a Quartz envelope ('bulb') filled with halogen gas to give an almost constant colour temperature. See Halogen Cycle.

Twist Lock Female Connector, 20A / 125V NEMA Cable Mount (from (USA only) A type of heavy-duty NEMA (US National Electrical Manufacturers Association) plug or socket which has a locking capability. They are available in different configurations for different current loads (15A, 20A, 30A, 50A).

Type of data cable consisting of multiple pairs of cable contained in a common sheath, often with a metallised screen around the cables to reduce interference. The fact that each pair of cables is twisted together also helps with rejection of errors and unwanted electrical interference / noise. Originally used for telecommunications, it is now used as computer network cable, where it's known as Cat5 or Cat6 (short for Category) cable. 
Wikipedia entry

A two-way adaptor. See GRELCO.

Uniformly Distributed Load. Some flying systems might have a UDL rating stated per bar, which is the maximum load that should be applied across the full width of the bar. A Point Load might also be shown, which is the maximum weight of a single item (or load) on the bar. 
See also WLL (Working Load Limit). 

UV Cannon by Prolight Concepts, UK Short wavelength source of light at the end of the visible light electromagnetic spectrum which causes specially treated materials to fluoresce on an otherwise blackened stage. Used for special effect and for lighting onstage technical areas (eg Fly Floors). Ultraviolet sources designed for stage use are known as Black Light sources and have all harmful radiations filtered out. They produce UV-A radiation, which is also present in sunlight, and is invisible to the naked eye;  in black light sources, the amount of UVA is far lower than you'd experience outside. UV-B radiation is far more harmful, and is not present in black light sources.
However, some high-intensity black light sources can be harmful to the eye so must not be used at close range to people, or where people could face the light source for any more than a few minutes. Use them to light scenery or props, or performers at a safe distance.
Black Light is used extensively in the Czech Republic where stunning effects are achieved on stages lined with black velvet. See the Image Theatre website for more.
Image Theatre website

An individual instrument (lantern / luminaire) on a lighting plan may be given a Unit number, which is a unique number for it in the lighting design or visualisation software. This is not the same as the dimmer number or DMX number. 

In lighting control terms, at least, a Universe is a single output of DMX512 control signals.
Each DMX Universe can control up to 512 channels (which is why the full name of DMX is DMX512). Some lighting desks can only control one universe. More modern desks can control multiple universes, and have multiple DMX outputs. When patching a control channel on the desk to a DMX output, you have to specify which universe, as well as which DMX channel. So, DMX channel 42 on Universe 1 would be 1/42. More complex control setups, using the more powerful ArtNet system can control a huge number of Universes from a single control system, enabling (for example) large numbers of dimmers, moving lights and individually mapped LED pixels to be operated simulataneously. 

Light from below the actors - from a light source on the stage floor.
French: contre-plong

End-On Stage Layout Plan ( 1) The part of the stage furthest from the audience. It's called Upstage because on a raked stage the stage slopes down towards the audience to improve sightlines. The furthest from the audience is literally higher due to the slope of the stage, so moving from close to the audience involves walking up the raked stage, towards 'Upstage'. 
US = Upstage, USC = Upstage Centre. USL = Upstage Left. USR = Upstage Right (see diagram)
2) When an actor moves upstage of another and causes the victim to turn away from the audience s/he is 'upstaging'. Also, an actor drawing attention to themselves away from the main action (by moving around, or over-reacting to onstage events) is upstaging.

United States Institute of Theatre Technology.
Founded in 1960. Publisher of Theatre Design and Technology and Sightlines journals, which are available online (see Publications in the Archive section).
USITT Website

Trade name for a range of 'intelligent' moving lights and control equipment. Identified by VL numbers. The VL1 model was introduced in 1980 for a Genesis tour by Showco, USA.
Vari*Lite Website

A trade name for an autotransformer (formerly) used to dim lighting by tapping a selected reduced voltage off the transformer's winding. Not to be confused with resistance dimming.
Submitted by Peter Neilson

Acronym for Visual Display Screen (or Video Display Screen). Sometimes used to describe any monitor / screen, but the term is a bit archaic now. 


(Trade Name) Moving light control console made by Vari*Lite.
Vari*Lite Website

A cue taken by a technician from the action on stage rather than being cued by the stage manager. Often abbreviated to "Viz" or "Vis".


The pressure at which electric current is available. The UK standard voltage is 230 Volts alternating current (AC). The American standard is 120 Volts AC.
The scientific name for Voltage is Electromotive Force. The frequency at which the current alternates (between positive and negative) is measured in Hertz (Hz) and in the UK is 50Hz, and in the USA is 60Hz. 
Named after Italian physicist Alessandro Volta (1745-1827). 

German Professional Lighting and Sound Association.
VPLT Website

Wireless DMX Protocol. 

A member of the (usually) stage management team who walks around the stage on the request of the lighting designer to enable them to see how the lighting coverage is looking. It's a common mistake to focus lighting on the stage floor rather than on the performers faces, so using a walker means they can check for lighting dips. 

1) (Trade name: ADB) The first zoom profile spotlight with ring control and 4 framing shutters which are fully rotatable.
2) "Warp and Weft" refers to the threads in a piece of fabric, or the fabric itself.
ADB lighting website

1) A lighting cover over the whole stage (e.g. 'We'll use the red wash for the hell scene'), usually from multiple sources. If this is the main lighting for the show, it's called the GENERAL COVER. 
2) A lantern which produces a large spread of softly focussed light, especially with moving lights (e.g. the VL4 and Mac 600 are wash luminaires). See also SPOT.
Designing and Focussing a General Cover

Device which produces a thin haze in the air by 'cracking' water droplets.


Unit of electrical power derived from the current (or 'quantity' of electricity) multipled by the voltage (or 'pressure' at which the current is delivered). Stage lighting equipment is rated in Watts (or Kilowatts - 1kW being equal to 1000W). This refers to the amount of power required to light the lamp. A higher wattage lamp requires more power and gives a brighter light output.

The distance from one point on a vibrating wave to the same point on the next wave. The lengths of the sound waves (wavelengths) we can hear range from one inch to 40 feet. High frequency sounds have short wavelengths (and are more directional), low frequency sounds have long wavelengths (and are less directional). In lighting terms, blue light is short wavelength, green is medium and red is long wavelength. Beyond visible light are the short wavelength Ultra Violet light and the long wavelength Infra Red light. Wavelengths of light are measured in Angstroms.

(Film Lighting) Array of Fay lights (14 x 14) used on a crane or cherry-picker to provide a high intensity long-throw light source for night shoots. Invented by cinematographer David Watkin, and named Wendy at his suggestion. 

A role is said to be 'white glove' if the person is not required or expected to help with setting up equipment, only in the operation of it. 

Pre-metric standard thread for bolts and associated fittings in the UK. (Pre 1972)

Colloquial term for so-called 'Intelligent' lights with moving mirrors. Also known as WAGGLY MIRROR. 

1) The out of view areas to the sides of the acting area (known as FLÜGEL in German). The wings are best identified by their position on stage (e.g. "Clive exits through the downstage left wing") but they can be identified by number if there are too many exits, with the downstage wing starting as 1, with stage left and right added to identify the side (e.g. "Sarah exits 2L").
2) Scenery standing where the acting area joins these technical areas.

A way of transmitting DMX data from a lighting control to lighting instruments without cabling. Ideal for events and short-run shows, but in large spaces where radio microphones and lots of audience members with mobile devices also using wifi, the technology is not reliable enough for permanent installation, especially where it is going to ruin the show if a fixture suddenly stops working or turns on at full when it should be off, when it loses data. The transmitter is connected to the lighting control desk by DMX cable or by ArtNet / SACN. Some equipment is now manufactured with wireless DMX capability built-in. The time saved can be very significant, especially for outdoor, battery-powered (rechargable) fixtures, which may be used to light trees / shrubbery for an event. The equipment can be set up and operational in minutes rather than the hours it would take to run in DMX cabling safely.

Another name for Ultraviolet light, produced using a discharge lamp inside an envelope of intensely pigmented glass known as Wood's Glass. It was invented in 1903 by American physicist Robert Williams Wood (1868-1955) and allows ultraviolet and infrared light to pass through it while blocking most visible light. It was developed as a filter to use for communications during World War I. 

1) High-brightness efficient non-dimmable lights used in a venue when the stage / auditorium lighting is not on. Used for rehearsals, fit-up, strike and resetting. The working lights are often controllable from a number of locations around the stage, including at prompt corner. As the working lights are on during rehearsals, set sessions, and during the day, they should be efficient light sources (e.g. LED or discharge lamps) rather than older types of lamp which are high-wattage. An instruction to 'Kill the Workers' solely means to turn the working lights off, rather than something more sinister. 
German: arbeitslicht
Some venues have an additional type of light source on stage solely for rehearsals, which may be less bright / intense, and more directed towards stage level rather than up the walls - these are sometimes known as Rehearsal Lights
German: probenlicht
2) Low wattage blue lights used to illuminate offstage obstacles and props tables etc. Known as 'Wing Workers', 'Blues' or 'Running Lights'.

American for SPANNER.

Acronym of 'What You See Is What You Get'. Mainly used in the context of a software tool for lighting design and production administration. Capable of stunning 3D rendering of lighting states, and direct connection to a lighting control desk. Enables accurate pre-visualisation of lighting designs and greatly increases the understanding between director / producer and lighting / scenic designer in the early stages of a production.
WYSIWYG product details

High output discharge lamp commonly used in Strobe lighting. Some followspots also use Xenon lamps. Xenon lamps have colour temperature of between 5600 - 6500°K.


Neutrik XLR Cable connectors from Canford Audio (UK) Multipin metallic connector. (3 pin for normal sound use, 5 pin for DMX, Colour Scrollers etc). Sometimes called Cannons after the original manufacturer.
The audio standard for wiring the 3 pin connector is as follows : Pin 1 (Screen), Pin 2 (+ve / 'hot'), Pin 3 (-ve, 'cold'). (Xternal, Live, Return).
A 5 pin connector for DMX512 use has the following connections: pin 1 = screen, pin 2 = data -ve ('cold'), pin 3 = data +ve ('hot'), pin 4 and 5 are not used by many manufacturers. A comparison is made between the signals carried by the two data cables, and any differences are cancelled out, meaning that noise/data error reduction is very effective.
The connectors are available as either plug (with pins, sometimes known as Male) or socket (sometimes known as Female) variants, and are available as cable mounted (most common) or panel-mounted. The use of gendered terms (Male and Female) is being reduced as the industry catches up with the modern world. 

US term for yellow plastic cable ramp sections.

A device used for remotely moving a gobo in one plane whilst it is in the lantern. Gives the effect of a lateral movement (door opens, train passes etc.). Made by DHA Lighting.
DHA Yoyo at Backstage Heritage Collection

The TRUNNION ARM of a lantern.

Zarges Skymaster Plus 3 part ladder (Zarges website) (Manufacturer) German manufacturer of a range of ladders. Commonly refers to the 3-part ladder used on many stages around Europe.
Zarges website
Access Equipment

(Manufacturer) UK-based manufacturer of control and dimming equipment.
Zero 88 website


A type of profile lantern with two lenses enabling the adjustment of both size of the beam and whether it's hard or soft focus. This adjustment of focal length allows a single instrument to find many uses in various locations around the stage. The flexibility is also essential when working with gobos. Also known (in the US) as a Zoom Ellipsoidal.