A moving circular mask that opens to reveal a scene or that closes to conceal a scene is called

Question

Quizplus · Accepted Answer

An iris is a circular mask that can be used in film and television to open or close to reveal or conceal a scene. It is named after the iris of the eye because it works in a similar way, opening and closing to control the amount of light that enters the camera lens. Neither A) an eye mask, B) a lens, nor C) a filter specifically refer to a circular mask that opens and closes in this way.

A Moving Circular Mask That Opens to Reveal a Scene