Dimming and control
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 ...