Connection Diagrams

Information coming soon 

Live Feed Camera - Static

Domestic-quality video cameras can be used to create a live feed from the stage (or an adjacent room) to a digital projector. A reasonable quality of video picture can be obtained by using a standard microphone cable with a pair of XLR to Phono adaptors to connect into the video camera output and the projector input. A cable length of around 20 metres gives a good enough signal. If you have a higher budget, you can use professional equipment with a high quality BNC video output connection, with BNC video cables, over a much longer distance. You'll still need an adaptor to connect into the video input of the projector.

Choosing a Projector

There are a number of factors to consider when choosing a data projector.

1. Throw distance (available distance between the projector and the projection surface) The closer to the screen, the brighter the image. This is sometimes expressed as a Throw Ratio. For example, a throw ratio of 2.5 means that to achieve an image 2 metres across, the projector must be (2 x 2.5 = 5)  5 metres from the screen. A projector 8 metres from the screen will result in an image (8 / 2.5 = 3.2) 3.2 metres across. A short throw projector with a ratio of less than 1 will produce a larger image for a smaller throw. The throw ratio of a particular projector model can be found at www.projectorcentral.com Example Throw Ratios and projection width, for a distance of 5 metres between projector and screen: Throw Ratio of 0.48 = image size 10.42m [5m / 0.48 = 10.42m] Throw Ratio of 1.44 = image size 3.47m [5m / 1.44 = 3.47m] Throw Ratio of 1.73 = image size 2.89m [5m / 1.73 = 2.89m] Throw Ratio of 2.04 = image size 2.45m [5m / 2.04 = 2.45m]
2. Required image size  The largest image will need a short throw projector with a wide-angle lens - originally designed for uses such as interactive whiteboards, where the projector is mounted only a short distance from the screen, they have a large number of uses in entertainment applications.
3. Noise level of projector Measured in dB (decibels), the lower the number, the quieter the projector fan. Many projectors have an 'eco' mode, which saves energy and extends lamp life by running the lamp slightly dimmer than usual. It also reduces the fan speed, so is quieter.
4. Contrast ratio Expressed as a ratio (e.g. 1000:1 or 20,000:1) it is a comparison between the brightest and the darkest areas of the image. A higher ratio results in purer black tones, which is essential to reduce the 'digital grey' box that projectors produce when they should be projecting black.
5. Brightness Measured in lumens. A standard office-quality projector may be capable of producing 2000 lumens. More useful projectors for darkened theatre spaces are 4000 lumens. The best quality projectors that have to fight through stage lighting states may be 10,000 lumens and above. ANSI Lumens (American National Standards Institute) provide a more accurate measure for the useful brightness of a projector, and should be quoted for all new projectors. Beware that many online sellers exaggerate the lumen  rating of projectors - if the projector is very small, and claims to have a high lumen rating, and be suitable for watching movies, use caution before buying!
6. Connections into projector Modern projectors have HDMI connectors which produce the best quality. Check the connectors your multimedia player / PC / Mac has, to ensure the projector is compatible.

Websites such as www.projectorcentral.com allow you to easily select a projector using these criteria, and also has an incredibly useful throw distance / image size calculator, which shows what each model of projector is capable of.

Keystone Correction

This is 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. Qlab (and other projection software) can also provide keystone correction and mapping of an image to a complex object. 

Projecting onto the Ceiling or Floor

Projectors should not be tilted more than 30 degrees from the horizontal. You can use a deflector mirror to project the image either up or down from the horizontal projector. A front-silvered mirror should be used. Ensure that the mirror you buy can be safely and securely mounted to the projector / lens.

Projecting from behind a screen

All modern projectors have a 'mirror' / 'flip' / 'reverse' option in the Image or Picture menu, which will enable you to mirror the image, either horizontally or vertically (or both) as required. Normal front projection is the only option if you're projecting onto a hard surface / flat, or if you need the projected image to shine onto actors costumes. However, if you have enough depth, you can use a wide-angle projector (with a throw ratio less than 1) behind the set, and can use rear projection material / fabric to project onto. This material is designed to show a bright image, and appears brighter and sharper than the same image projected onto a painted surface from the front. The image also is not affected by actors in front of the screen. 

Blocking 'Black' Light from a projector

The contrast ratio of a projector is a measure of how 'black' the dark parts of the projected image can be.This includes the black that Qlab projects when there is no video playing. Cheaper LCD projectors (with, for example a contrast ratio around 400:1) have a visible dark grey beam which can be intrusive during blackouts. A projector using DLP technology can produce a much better contrast ratio, of around 2500:1. A professional high quality projector may have a contrast ratio of 10,000:1, producing very dark blacks, and an almost invisible blank screen. If you're only able to use a projector with a poor contrast ratio, you can use a dowser to block the light.
CARDBOARD FLAP: The most low-tech way of achieving this is to use a piece of cardboard attached to a piece of string, taped onto the projector so that when the string is released, the cardboard flaps over the lens, blocking the light.
OLD CD-ROM DRIVE: Old CD-ROM drives from redundant computers can be modified into very effective dowsers. [Advice follows for technically-minded folk]: Open the case of the CD-ROM and remove (and recycle at your nearest facility) the electronics, apart from the motor drive for the CD drawer. Solder cables to the motor, and run to a suitable connector that you've mounted on the CD-ROM body. Apply 5V at one polarity and the drawer opens. Reverse the polarity, and it closes. Cover the hole in the CD drawer with blackwrap tape or other suitable heat-resistant material.
DMX DOWSER: A number of companies make DMX-controllable dowsers which fit onto the front of a projector and have a motor and a shutter which lowers to cover the projector lens.

• Bakerwood ProDowser
• Flapper Blacky
• Wahlberg Projector Shutter

Pocket Size Projector

A wide range of 'pico' projectors are now available, many with the following features:

• LED light source
• HDMI connection
• Internal rechargeable battery
• Memory card (often Micro-SD)
• Media Player (to play back photo gallery, videos, and even Powerpoint presentations)

While the brightness cannot compare with larger desktop projectors, the possibilities of using a handheld projector (or headworn, or mounted inside a prop, or hidden in a small room as part of an installation) are endless. They are usually nearly silent-running, so are perfect for small venues. The brightness of these projectors are measured in lumens, so this is the critical information to find out before buying.

LED Curtain 

Flexible curtain embedded with multiple LED sources which can be mapped to show video images.

Using TV screens on stage

Modern TVs can accept an HDMI input, so can show a signal from a laptop or video camera (or vision mixer).  Information about older TVs will follow shortly.