Cheap LED fixtures
Normally, we stay far away from anything marketed to DJ’s, but we’ve been experimenting with cheap LED fixtures as an inexpensive way to put more colors on stage. LED fixtures have a few advantages: they efficiently produce light without much heat, they don’t require a dimmer, and they can produce multiple colors without gel changes. They also have some disadvantages. Color mixing is produced by combining LED’s of different colors (RGB) at different intensities, so the color is only “mixed” at the surface it is illuminating. It can be difficult to produce white light that matches light from other fixtures. LED’s cannot be dimmed by lowering the voltage, like a conventional light. Instead the LED is strobed (pulsed) at a rate too fast for your eye to discern. Unfortunately, the Chauvet ColorPalette fixtures shown below use a pulse rate that is slow enough that it can be picked up on a video camera. When the fixtures illuminate a set piece like this one, which is in the background of many IMAG shots, the flicker is very distracting if the intensity is run at anything less than 100% 
Practically speaking, when a Color Palette is visible on camera,we can only get seven full-intensity colors: red, blue, green, white, purple, blue-green, and yellow. We’ve since moved them out into the auditorium where they are used to illuminate the walls. We did find one really cool application for these lights. We have a number of deep-purple, “blacklight” Color Palettes mounted backstage to enable people to move in the dark. They stay on all the time, draw very little power, and are totally invisible to the audience, even during a dead blackout. 
This is a Chauvet COLORado 1, which is meant to replace a small par can. It’s mounted on a pipe above and behind the musicians and lights them from behind. This is the view you get from the front row in the audience. See the red, blue, and green LEDs? That’s producing white light, but you wouldn’t know it from this angle. That’s what happens when the colors don’t mix at the light. We don’t have the strobing problem on video with the COLORado’s, but I don’t know if that’s due to their positioning or their design. For more information, see the LED lighting reviews by onstagelighting.co.uk. There are also pro-grade LED fixtures that are much better…but I haven’t used them.
Comments
Comment #1 by Ben
Ben - Mar 2, 2014
Hello, have you found a way to get around the IMAG flicker by changing the refresh rate of the cameras? Thanks!
Comment #2 by Craig
Craig - Mar 2, 2014
That’s an interesting idea-we never tried that approach. We just focused the lights so that the camera only saw diffuse reflected light. I suspect that the flicker is actually the “beating” produced by the combination of the camera refresh rate and the flicker of the LEDs. I suppose you could tune either frequency to modify the beat frequency and reduce or eliminate the flicker.