Today’s lighting designers take for granted the ability to access multiple colors from single lighting fixtures. Gone are the days that working with large color palettes meant truckloads of par cans and enough truss to construct a skyscraper. But, with the exception of the mechanisms used in follow spots, color changers are fairly new on the scene.

Color changers can be divided into several categories. They may be divided by the type of mechanism they utilize, by filter material (gel or dichroic), and by whether they bump colors or are capable of crossfades or color mixing. Color mixing can be either additive or subtractive. Additive systems generally use separate lamp sources of the primary light colors red, green, and blue (RGB), as in your color TV. There are drawbacks to the additive system, including difficulty in creating pure white, inability to create narrow-band saturated colors such as vivid greens, and an inability to create colors beyond blue in the spectrum, such as violets or indigo. Subtractive systems use filters, often cyan, amber and magenta. Cyan, amber and magenta are secondary colors that result from combinations of equal amounts of any two of the primary colors. The benefits of subtractive systems include the ability to isolate fairly narrow bands of the spectrum, as well as the ability to open the filters to create pure white from the source. Drawbacks are dependent upon the filter material used in a given system.

As previously mentioned, the earliest color change mechanisms were those used in follow spots. These consist of a series of gel frames that may be pivoted in or out by the use of side-mounted levers. The most common use is for the addition of color correction filters, but cosmetic and other colored gels are used in both theater and concert designs. In most follow spots, colors may be either bumped in or slowly crossfaded. Unfortunately, the ability to change colors on precise cues is dependent upon the skill of the spot operators. In the case of theatre, long-running productions benefit from having operators that can learn the show and execute cues with precision, but concert tours have different operators of different levels of qualification at each show. Results can be very unpredictable. The greatest shortcoming of this type of color changer is that it requires a human operator, making it wholly unsuitable for most lighting applications.

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