Constant color temperature is particularly important if you are shooting digital. Digital cameras are extremely sensitive to minute shifts in the color temperature of your lights. It is important to understand that every time you change the flash power level on a flash unit, you also change the color temperature of the light. The current standard allows for a maximum deviation of 200 degrees Kelvin before you begin to see significant shifts in color. Conventional electronic flash units, without constant color temp., can have color temperature deviations of more than 650 degrees Kelvin from full power to 1/32 power.

For all practical purposes, if you have a one f stop difference between your main and fill light, the color shift probably will not be noticeable or can be easily cleaned up in your digital darkroom. However, if the main light is at full power, the fill light at 1/2 power, the background light is at 1/16 power and the hair or accent light is at 1/32 power, you may experience extreme variations in color. This will be apparent as a series of color crossovers that either cannot be neutralized, or will take a tremendous amount of time to clean up in the digital darkroom.

Constant color temperature lights are specifically designed to minimize shift in color temperature caused by changes in power levels. The Photogenic Solair and StudioMax III Constant Color lights will have a color temperature change of 50 degrees Kelvin over a six f stop range, and for the Solair lights a change of 150 degrees Kelvin over an eight f stop range. This is well below the maximum deviation standard of 200 degrees Kelvin.