180-degree shutter rule
Also known as: 180-degree rule, shutter angle rule
A filmmaking guideline: set shutter speed to about double the frame rate, such as 1/50 s at 25 fps, for natural motion blur the eye reads as smooth.
Updated
What it means
The name comes from film cameras with a spinning half-circle shutter. A 180-degree opening exposed each frame for half of the frame interval, and audiences grew used to the motion blur that produced. Digital cameras copy the look by setting shutter speed to one over twice the frame rate.
So 24 fps calls for 1/48 s (1/50 in practice), 30 fps for 1/60, and 60 fps for 1/120. The result is just enough blur on moving objects that motion flows from frame to frame, instead of the choppy, strobing look you get from a very fast shutter.
How it works in practice
The rule is easy to dial in and hard to hold in daylight. Action cameras and most drones have a fixed aperture, so at midday a 1/50 s shutter massively overexposes the image. The fix is an ND filter: drone pilots typically carry a set running from ND8 for overcast skies to ND64 or stronger for bright sun, and action-camera users clip filters over the lens cover.
Treat it as a guideline, not a law. Anything from roughly 1/40 to 1/100 s at 25 fps still looks natural to most viewers. When shooting a Log profile, many pilots also lock ISO at its lowest value and let the ND handle the light, so exposure stays consistent across a whole flight.
What to watch out for
The rule can fight against action-camera stabilization. A slow shutter on a vibrating helmet or handlebar bakes blur into each frame, and when electronic stabilization steadies the picture, the blur stays - the frame holds still but the image inside it smears. For rough POV runs, many shooters deliberately choose a faster shutter.
Other traps: fitting an ND but leaving the shutter on auto, so the camera picks whatever speed it likes instead of the one the rule calls for; keeping a strong ND on at dusk and getting noisy footage; and forgetting that slow motion follows the capture rate. A clip shot at 120 fps needs about 1/240 s, not 1/50.
How RawClip handles it
RawClip works with whatever exposure you shot, so the shutter choice happens in the camera. It accepts drone and action-camera clips up to 5.3K and 120 fps from different brands in one order, analyzes motion and peak action, and cuts the best moments into one highlight synced to music.