Dimming And Control
DOI link for Dimming And Control
Dimming And Control book
Before the introduction of electrical control of dimming, various methods of reducing the light level developed and many are still in use today. The two main disadvantages of electrical dimming is that by lowering the voltage to a tungsten lamp the colour of the light source changes, moving towards the red end of the spectrum, and secondly any colour filter that is placed in the luminaire will give a different result. The most exaggerated change will result with a heavy blue filter. When the source is running at full power it is producing light across the spectrum with some blue to penetrate the filter and provide blue light. When the source is dimmed down, the colour shifts towards the red end of the spectrum and produces very little blue, therefore the filter which restricts the red and green will pass little, if any colour. This is an important fact that all LDs learn early on in their career that the dimmer setting is just as important as the selection of the colour filter when designing the lighting plot.