Shutter Angle
A way of expressing shutter speed relative to frame rate, inherited from the rotating disc shutters of film cameras.
Formula / rule
Shutter speed = 1 / (fps × 360/angle)
Measured in
degrees
In depth
A 180° angle means the shutter is open for half of each frame's duration, whatever the frame rate — which is why cinematographers think in angles rather than fractions of a second. It keeps motion rendering consistent when the frame rate changes, since the relationship between exposure time and frame interval is what the eye actually responds to.
Examples in practice
At 24 fps a 180° shutter is 1/48 s; at 48 fps the same angle becomes 1/96 s.