I am in the middle of a project comparing various lighting colors to LED colors. I am finding some obvious differences but also discovering some interesting things. A big issue with using LED fixtures on stage or in event lighting is eventually we will need to match an LED fixture with a standard incandescent fixture with a gel. I am finding that RGB LEDs can get very close to most colors in a swatchbook.
But what do we do about the dreaded amber shift that happens when you dim an incandescent lamp down? There are LED fixtures that actually have an incandescent dimmer curve programmed into the software that, when dimmed, will emulate the “reddening” of the color or amber shift that happens naturally when the filament cools. These are very impressive but are really a stop gap measure to duplicate an all incandescent rig which will eventually go to obsolescence.
These artificial dimmer curves work well for mixing the two technologies but lighting designers are going to have to face the fact that LED “cleaner” dimmer curves are going to become the norm and that cross fades between cues will change visually. This is not a bad thing! In the incandescent days, I spent lots of time and effort smoothing out a choppy cross fade or keeping the stage from going to darkness when using poorly trimmed dimmers. The new technology will help that. One of the idiosyncrasies is that certain primaries will be seen by the eye sooner than others, so you may see a red or green tint earlier than the other colors. These issues will be different from fixture to fixture but our eyes will forgive a lot of the peaks.
As a designer, you can start planning for this eventuality by borrowing, renting, or buying an RGB or RGBA DMX controlled LED fixture and experimenting with primary color mixing. I would highly recommend using only a basic RGB fixture to work with because it may be the only fixture that a theatre can afford initially and will be more common than the RGBA, RGBW, or the seven color mixing fixtures. You will be quite surprised at the color range that these fixtures can hit. Adding an additional amber channel will help to create the warmer tones but is not absolutely essential. I am firmly convinced that over the next 20 to 30 years standard incandescent theatre fixtures will be replaced by LED sources. We may as well get ready for that evolution and start working with the toolbox.