The discharge lamps used in most intelligent luminaires can not be dimmed by ordinary voltage regulating dimmers, and dimming has to be effected by mechanical dimmers incorporated into the luminaire. There are three basic methods used to mechanically dim moving lights:

A one-flap system: As the flap covers the aperture, the light is dimmed.

A two-flap system: The two flaps overlap until a total blackout is achieved.

A glass disc: A rotating glass disk is gradated from clear to black. As it is rotated, its position determines the amount of light allowed to pass through it.

These dimmers are efficient and allow fast or gradual fading of the light, as well as blackouts, flashing or snap.