Pro AV Logo Originally published as a Consultant's Connection
column in Pro AV Magazine
  April 2004

Getting Lit: An Enlightened View

Lighting for AV and videoconference spaces should address AV, architectural and ergonomic needs.

By Tim Cape, CTS-D

Have you ever walked into a broadcast studio that looked like a meeting room? I haven’t, except where there was a corner of the studio set up for it and the rest of the room was all pipes, booms, lighting stands and cameras on pedestals. It was still a broadcast studio, and appropriately so. On the other hand, have you ever walked into a meeting room that looked like a broadcast studio? I have, and it isn’t so appropriate, especially when it’s supposed to be an upper-crust boardroom.

Lighting for the Presentation and the Task

For a presentation system that doesn’t broadcast anything anywhere beyond the room it’s in, there are some basic issues that we need to address. For lighting, we need to have enough light on the occupants’ task areas for them to take notes, for example, but we don’t want excessive light on the front projection screen in the room that could wash out the image.

There are many parameters to consider, but based on the display type (front or rear projection or direct-view like plasmas and CRTs) and the application at hand, one criterion we need to maintain for instance is a minimum contrast ratio of 10 to 1 for the video image that is displayed. More is better, and for direct-view displays this is easy to do even with a fair amount of light falling on the display. For front projection images, however, this can be hard to do if we still want to keep lights on for note-taking since front projection screens are designed to reflect light, whether it’s from the projector or a light fixture in the room. Though some projection screen materials can improve this arrangement, lighting in the room can’t be ignored.

On the plus side, it’s relatively easy to make the room work for front projection which is often just a matter of zoning the lighting so the fixtures nearest the screen can be turned off separately from the rest of the fixtures in the room. However, if the fixtures are of the indirect type that throw broad pools of light on the ceiling rather than directing controlled light downwards (most often using louvers), we can still end up with too much light on the screen even with some zoned lighting areas.

A good rule to keep in mind: Indirect lighting is incompatible with front screen projection environments. It’s ok to use indirect lighting for most direct-view display environments, but most front (and some rear) projection systems will be significantly degraded. Spread the word.

As Lighting Goes, So Goes the Image

Though it’s relatively easy to create an acceptable lighting environment for the presentation, we take a quantum leap in warp speed when we introduce the function of videoconferencing into a presentation room. Trying to keep a videoconferencing room looking like a meeting room while trying to make the outgoing image look like it came from a broadcast studio is one of those things one needs to consider, and consider carefully. Good lighting is what will prevent the audience and presenters from looking like raccoons at the far end of a videoconference. You may be sending out a picture, but is it a good picture?

Whereas 20 years ago we had to provide light levels of 100 footcandles on the participants in a videoconferencing room to maintain good video signal to noise ratios, today we can get by with half that and get a good picture—if that 50 footcandles is at the correct angle and if we have a way of filling shadows on the smiling faces of those on camera. The trick here is to get the light levels we need on the surfaces that need lighting without looking like a broadcast studio since these are, after all, still “just” meeting rooms. And employees, students or presenters won’t tolerate the kind of lighting that broadcast talent is used to.

Getting the right lighting in the right place can be even trickier when we have to light both a presenter and an audience area for video camera coverage while the presenter is standing next to a front projection display. In these cases we may have to go beyond a purely architectural solution and make use of products that are more broadcast-like, but careful selection and placement of the fixtures can minimize their tendency to make the room feel like the set for the David Letterman Show.

Lighting the Way

Whether we are designing rooms for simple AV presentation or for more advanced functions such as videoconferencing and distance learning, we have to do just that: design the room. Pro AV is not just about creating an electronics system, it’s about creating an environment. A key (so to speak) aspect of that environment is lighting since it is the vehicle for half of the audiovisual experience and we need to be concerned about how light waves are bouncing around the room just like we need to be concerned about how sound waves are bouncing around the room.

So being enlightened means seeking architectural solutions with architectural aesthetics to solve the broadcast lighting problem for pro AV facilities. There are a variety of specialty fixtures that allow for us to provide key, fill and back lighting in a meeting room without using a pipe grid, theatrical instruments and barn doors to get what we want, but as designers we have to know the available products and how to use them or find someone who does. One of the industry efforts that will help in designing these kinds of spaces is a guide that is being developed by the Committee for Lighting for Videoconferencing and Presentations (of which I am a member) under the Illuminating Engineering Society (IES North America). Look for this design guide to be finalized and available from the IES later this year.

 

 
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