Shutter angle

Simulator

AI generated demo imageYour photo stays on your device. This page opens it in your browser and works on it there.

How shutter angle works

Film cameras expose each frame through a spinning half-disc. The size of its open slice, the shutter angle, decides how long each frame collects light, and so how much motion blur every frame carries.

• Shutter angle

  The open part of the rotary shutter, in degrees. A 180° shutter is open for half of every frame and closed for the other half while the film moves on to the next frame.

• Exposure time

  Exposure time = angle ÷ 360 × 1 ÷ frame rate. At 24 fps, 180° gives 1/48 s, 90° gives 1/96 s and 45° gives 1/192 s. Digital cameras often state this as a shutter speed instead.

• The 180° rule

  Half the frame interval is the cinema default because its motion blur matches how our eyes expect movement to look. Most films you've seen were shot this way.

• Narrow angles

  Under about 90°, each frame is a sharp, frozen slice with a gap of missing time between frames. Movement looks stuttered and intense, which suits battle and action scenes.

• Wide angles

  Above 180°, frames smear into each other. Movement looks soft and dreamlike, and you gain up to a stop of light. A full 360° is only possible on digital cameras; a film shutter must close while the film advances.

• Judder and the 7-second rule

  At 24 fps, a pan that's too fast jumps in visible steps. A common guide: an object should take at least about 7 seconds to cross the frame at 180°.

• Frame rate

  Higher frame rates sample motion more often, so movement looks smoother and more like live video. Shot at 48 or 60 fps and played back at 24 fps, the same footage becomes slow motion.

• Flicker from mains lights

  Lights powered by mains electricity pulse 100 or 120 times a second. Angles like 172.8° at 24 fps (1/50 s) line exposure up with 50 Hz power so frames don't flicker.