Which of the following is NOT a common type of dimming?

Frequency Modulated Dimming is not commonly recognized as a standard method of dimming in the context of theatrical and entertainment lighting. In the industry, dimming techniques are primarily categorized into several well-established methods that designers and technicians use.

Pulse Width Modulation (PWM) is a popular technique frequently employed to control the brightness of LED fixtures by adjusting the duration of the "on" and "off" cycles at a rapid frequency, creating the perception of dimming without altering the voltage.

Sinewave Dimming is another established method that controls the power delivered to the lighting fixtures by providing a smooth, sine wave output. This approach helps to minimize flicker and is often used in high-quality dimming systems.

Reverse Phase Dimming, commonly implemented in IGBT (Insulated Gate Bipolar Transistor) dimmers, works by cutting off part of the AC waveform to reduce power and thus dim the light. This method is widely recognized and utilized in many lighting systems.

In contrast, Frequency Modulated Dimming does not have a significant presence in common dimming practices, making it the option that does not belong among the others listed. This distinction is crucial for understanding the different techniques used in lighting and control systems within the entertainment industry.