The 180-degree shutter rule is a common starting point for motion that looks natural: set the exposure time to about half the duration of each frame. In everyday camera settings, that means roughly 1/50 second at 25 fps or 1/60 second at 30 fps. ARRI’s explanation notes that a 180° shutter at 25 fps gives a 1/50-second exposure. ARRI shutter white paper

Why the setting changes motion

Each frame records light over a slice of time. A longer exposure records more movement within that frame, creating more motion blur. A shorter exposure records less movement, which can make fast action look sharper frame by frame but may also look more staccato. The 180° convention is popular because it often gives a balanced motion impression, not because every scene must use it.

Quick examples

Frame rate	Approximate shutter speed at 180°
24 fps	1/48 second (often set to 1/50)
25 fps	1/50 second
30 fps	1/60 second
50 fps	1/100 second

If you want a sharper, more staccato action look, you might choose a shorter exposure. If you want more blur, a longer exposure may suit the scene. These changes also affect how much light reaches the sensor, so exposure may need to be adjusted. Under artificial lighting, check for flicker in a test clip before recording a full scene.

Treat it as a starting point

Choose your frame rate for the movement and delivery you need, then use the shutter setting to shape motion. For example, a creator filming a 25 fps interview can start at 1/50 second; a sports clip intended for slow motion might use a higher frame rate and a different exposure choice. Review the result on the display you will edit on rather than treating a formula as a substitute for a test.