Royce Allen Dudley, Producer, Director, Cinematographer at Movie Producers
Answered Aug 21, 2019 · Author has 2k answers and 1.1m answer views
“What does it mean when a movie director says, "Check the gate"?”
A more complete answer perhaps…
When a director (or likely 1st AD) says “check the gate”, it is an indication that they are satisfied with the takes of the shot at hand and prepared to move on so long as there is reasonable certainty the image is clean, which is achieved as described below.
The gate is the rectangular opening in a cinema camera that has lens and shutter in front of it and film pressed flat behind it.
When the final setup of a take is made, the gate is checked for hair or emulsion debris. This is done either by advancing the mirror shutter to “open" with the pinching knob and shining a strong light into the lens to inspect film plane, or by removing the lens and inspecting directly.
No cast or crew move on to the next setup until the gate is called good by a camera assistant.
If the gate is dirty, it indicates any prior takes may have visual damage or shaded frames, and so the gate is cleared ( cleaned ) and another take or more will be taken as safety coverage.
In the digital world, “check the gate" is still a thing, though not generally to clean sensor but to confirm playback and data integrity of last take before moving on.