Lighting Focussing

This is the key process which transforms a rig of lanterns into a series of creative tools perfectly arranged and set for the event.
The following assumes a rig of generic (non-automated) lanterns. If you have automated lanterns, you don’t need to focus them by hand!

First Things First

Beam Size: Generic lighting equipment (profiles, fresnels, PCs) will have at least one control on the lantern to make the beam bigger or smaller (and with profiles, harder and softer edged). With Fresnels and PCs, the focus knob is used to move the lamp and reflector relative to the lens (which remains fixed). With profiles, the focus knobs move the lenses, and the lamp remains fixed. So, it’s very important to be gentle when using focus controls on Fresnels & PCs – if the lamp is hot, it can easily be damaged with a jolt / knock. 
Beam Position: All generic lanterns can be adjusted to move the beam around the stage, as required. Horizontal movements (panning) are achieved by rotating the lantern relative to the clamp used to hold it on the bar. This is usually achieved by slightly loosening the bolt. Vertical movements (tilting) are achieved by undoing the tilt lock knob, usually on the side of the lantern. 

Before starting:

  • Darkness
    Ensure you have a time slot on stage where you can turn the working lights off and when no other work is taking place.
    Focussing has to take place in darkness, with no other distractions.
  • Locations
    Ask the stage management team to mark all locations where you need specials. You only want to focus the special on the chair once.
    If the position isn’t yet agreed (or needs the directors’ input) just do a quick rough focus. It’s possible the director will move the chair into the light (rather than requiring you to refocus). But it’s also likely they’ll want it refocussed.
  • During the Lighting Rig, the crew should have left everything ready to focus, with barndoors open, shutters out, and lanterns pointing roughly in the right direction. If they haven’t, do this first.

Getting started – The focusser:

  • Ensure your ladder or access equipment is positioned so you can focus from behind the lantern. Do not try to focus from underneath the lantern. 
  • Wear gloves (to protect against heat) and carry a suitable spanner (attached to a safety lanyard so it cannot drop) to ensure the lanterns are tightly secured in place.
  • Check every lantern has a suitable safety bond. 
  • Ensure the safety bond and cable for the lantern are not snagged or will not prevent the lantern from moving to the required position.
  • Make sure you can move the focus knobs before the lantern is turned on – loosen them in preparation for focussing each lantern. If you have to use too much force to undo / move a focus knob, you risk jolting the lantern which may cause the lamp to blow once it gets hot. 
  • Start with beam as small as it goes, and widen it to do the job you need (and no more). Don’t start with a huge beam and cut it down with barndoors and shutters.
  • Be gentle with the lantern. A focus knob on a Fresnel or PC may be directly moving the lamp inside the lantern. If the lantern has been on for a while, any sudden movements may cause the filament to break, wasting time (and money).

Getting started – LX team

  • Do not turn the lantern on until the focusser is in position and ready (to avoid the lantern over-heating, and reducing the chance of the lamp blowing if knocked while hot)..
  • Use working lights on stage to move the access equipment around. Never move equipment in darkness – keep the previous lantern on until they’re in position for the next one. 

Focussing using a Tallescope – Greenwich Theatre, UK

The Process – LX designer

  • The lighting designer should not face the lanterns when focussing. Use your shadow as a reference to see where the light is, not by staring into the beam. This will make your eyesight ineffective for a while.

Terms to communicate with the focusser.

The focusser should try to understand what the lighting designer is aiming for, with each lantern, so that this can be approximated, and then just tidied up by the designer, rather than having to describe every movement in great detail. It’s extremely helpful if the designer says ‘This is the next part of the general cover, following on from the last one’ or ‘this is a backlight on the downstage chair’ or ‘this is the front light on the throne for the finale’, the focusser can get ahead.

The lighting designer (who should be on stage, walking around and looking at the effect of the light from the audience and on stage), gives a seemingly bizarre series of instructions to the focusser:

  • Spot that (make the beam as small as possible)
  • Flood that (make it larger)
  • On Me (centre the beam on the head of the lighting designer)
  • Onstage a touch (move the beam of the lantern towards the centre of the stage)
  • Offstage a bit (move the beam towards the nearest wing)
  • Lift that – tilt up
  • Drop that – tilt down
  • Flag that – the focusser should wave their hand in front of the beam to enable the designer to see the extent of the beam (especially useful if you’re focussing with multiple lanterns on at the same time, or comparing lanterns which form part of a wash).

Some teams use hand signals to communicate between the designer and the focusser, especially if the environment is noisy or if there are multiple activities going on at the same time (or multiple lanterns being focussed simultaneously). However, a simple verbal command is often less open to misinterpretation. As many hand gestures do not carry the same meaning in all countries, if you’re touring internationally, it’s best to agree signals and meanings beforehand with the crew. 

Before moving on – LX designer:

  • Ask a ‘walker‘ to move around on stage so you can check the coverage before moving on.
    • Is the area adequately lit (paying attention to the actors’ face)
    • Is there any unwanted spill light (e.g. on curtains or off the stage)
    • Does this lantern overlap enough with any others that it has to blend with?
  • Use spike tape to mark the location the actor has to stand in any specials that haven’t already been marked by the director.
  • The lighting designer should check focus from the audiences’ point of view to make sure stray light isn’t (for example) all over the proscenium arch, or lighting masking flats etc.

Before moving on – Focusser:

  • Ensure the lantern tilt and pan are securely locked, using tools if necessary.
  • Make sure any gel required is inserted securely, and that there’s an air gap between the gel and the lens. This will help to prolong the life of the gel.
  • Dress‘ the barndoors (if fitted) to ensure that the lantern looks correct. This involves bringing the barndoors in to just beyond the edge of the beam if they’re not being used to cut off the beam.
  • Ensure that the lantern beam is not obstructed by anything – if the beam is pointing at the back of a nearby cloth, or even the cable of an adjacent lantern, it can cause a heating effect that can damage and even potentially start a fire.

Access Problems

If a particular instrument is not reachable using ladders or other access equipment, a bounce focus can be used. The lighting bar is flown in, and the instrument is given a rough focus, before flying it out again and seeing how it looks. this process of flying the lantern in and out is repeated until the correct focus is achieved. 

See also

Designing and Focussing a General Cover

Author: Jon Primrose. 
First written September 2016
Last updated: August 2022

Keywords; focus lights, focussing lights, focussing lighting, focusing lighting, focusing lights, how to focus lighting rig focus, effect only certain part stage lit. tilt knob, pan, focus rig, focusing a rig, lamp movements,