Shutter Angle

What this is about

The unit survives because it scales: a film camera's spinning mirror shutter was open for a fixed slice of each rotation, so 180 degrees always meant half the frame interval — at any frame rate. Digital cameras kept the convention because it keeps motion character constant when speeds change: set 172.8 or 180 degrees, ramp from 24 to 48 fps, and the blur per frame keeps its proportion. DPs think in angle for look — narrow angles for gritty action, wide for smear — and let the camera translate to fractions of a second.

A term only helps when everyone on set means the same thing by it — so what follows is how it is used, not a dictionary definition.

What runs differently here

In planning terms, that means:

• Angle and speed describe the same thing: 180 degrees at 24 fps equals 1/48 second.
• Angle stays constant across frame-rate ramps; a fixed fraction of a second does not — that is its advantage.
• 172.8 degrees is the classic European trick against 50Hz lighting flicker when shooting 24 fps.

With TillyGen

TillyGen's shot list keeps a camera-settings column where deviating shutter angles are noted per shot, so intentional looks survive into the shooting day.

Change one constraint and the consequences travel through the whole plan: affected shots are flagged, the call sheet is regenerated, and nobody keeps working from yesterday's version.