Since its inception, production lighting has strived to simulate natural settings such as dawn, sunset, a full moon, lightning storms and fire. Objects look different under each of these lighting conditions. Lamp technologies and luminaire designs have evolved under the influence of these differences.

Objects absorb certain wavelengths of light and reflect others. The color of an object is defined by what it reflects. Because objects can only reflect what is shone onto them, their color is further defined by light sources.

Color filters have been in play since the dawn of production. While gels are still tremendously popular, the technological advances are occurring primarily in the area of dichroics.

Color correction is an ongoing concern and will remain so unless everyone agrees upon a singular lamp source. Most of the more upscale automated fixtures are now including CTO dichroic filters in their color systems. A more recent development is the incorporation of variable CTO and CTB dichroic filters, providing a means for compensating for lamps of differing color temperatures and for calibration of white balance as the lamps age.

While these sophisticated tools can filter out color inconsistencies, they can’t effectively add color that is not in the source to begin with. The different CRI values between lamp types present a tough challenge in critical applications. Lamp manufacturers have come out with new arc source lamps (CDM, for example) with color temperatures and CRI values that are very close to tungsten sources. More and more manufacturers are coming out with tungsten source automated lights to blend in with the enormous installed base of tungsten conventional fixtures.

In theory, proper amounts of the subtractive colors, cyan, yellow and magenta, can produce every color in the visible spectrum. This presupposes a perfectly even white light source and perfectly tuned filters. In reality, it is difficult to fine-tune a system well enough to achieve this. The nonlinear aspects of the lamp sources themselves preclude even a laboratory model. Some designs have compensated for this by shifting the secondary component colors away from CYM to achieve certain popular colors, to the detriment of other, less popular ones. Just as printers use black to augment CYM color-mixing systems (CYMK), the trend is for optical engineers to add color wheels with discrete colors to CYM systems to fill in the gaps. A more recent development is the addition of a fourth variable density color wheel, providing perhaps the widest range available.

The growing trend toward using LEDs as a color-changing production lighting source is backed by several key attributes of the technology. Top on the list is the potentially long life that LEDs can have. If the elements are cooled properly there is potential for LEDs to last as long as 100,000 hours. That is 16 times as long as a CDM lamp (6,000 hours), the next runner-up—if you don’t count neon. The high efficiency of the elements allows for smaller power supplies, smaller housings, lower weight and money saving on power consumption. The relatively small amounts of radiant heat generated by LEDs require less cooling, thereby potentially reducing noise and size.

The trade-offs include high up-front costs and color instability over time. The output of red, green and blue LEDs degrades at different rates. Over time, the color balance of an RGB LED system will shift, requiring recalibration of control programs in order to maintain consistency. The relatively low-watt densities make it difficult to harness an LED’s light for focused optics. LED component manufacturers are working on new lenses and technologies to address the issue. My belief is that this technology will continue to advance and be widely adopted.

Throughout all of these technologies for coloring light, there emerges a common goal, to be able to harness and manage white light itself.


John McDowell has been involved in the entertainment side of the lighting industry since 1985. He can be reached at john@austinworldmusic.com.