Chroma key, known as bluescreen, greenscreen, or process photography, is a method of producing mattes for compositing. Optimum exposure levels for the green or blue screen depend on the nature of the subject and the setup. Different visual effects houses will have varying preferences that may be based on the hardware/software combination they use. The input side of most dimmer packs are Camloc connectors. Frequently the neutral is reversed; the easiest way to run into trouble with dimmer orders is to forget to order feeder cable with the neutral reversed or “turnarounds”: female to female connectors. Analog dimming is simpler, but the variable current supplied to the LED means that the regulator supplying the current to the LED must soak up any power not going to the LED. Flicker is a major issue when shooting high speed.