What is the 180-degree shutter rule?

The 180-degree rule sets the shutter speed to 1/(2 x fps). At 24fps, that is 1/48s. At 30fps, 1/60s. This produces the amount of motion blur that audiences perceive as natural and cinematic. It comes from film cameras where a 180° rotating shutter exposes each frame for half the frame period.

Why would I use a different shutter angle?

90° (1/96s at 24fps) reduces motion blur for a sharp, intense look — used in action sequences like Saving Private Ryan. 270° (1/32s at 24fps) increases blur for a dreamy effect. Higher angles let in more light, useful in dark environments.

Does shutter angle affect exposure?

Yes. Wider shutter angle = longer shutter speed = more light. Going from 180° to 90° halves the light (1 stop). Going from 180° to 360° doubles it (1 stop). This makes shutter angle a creative and exposure tool simultaneously.

How does shutter angle relate to ND filters?

To maintain 180° shutter angle in bright conditions, you need ND filters to reduce light. Without ND, you might need 45° (1/192s at 24fps) to avoid overexposure — resulting in unnaturally sharp, stroboscopic motion. ND filters are essential for cinema-quality outdoor video.

PhotoCalcs

Shutter Angle Calculator — Cinematic Shutter Speed

Convert shutter angle to shutter speed for cinematic motion blur at your frame rate.

Frame Rate

Shutter Angle

180° is standard

How We Calculate This

Shutter Speed from Angle

Shutter speed = 1 / (fps x 360 / angle)

At 180° and 24fps: 1 / (24 x 2) = 1/48s. The 180° rule produces natural motion blur for cinematic work.

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Last updated: February 2026

All calculations are estimates based on standard optical and photographic formulas. Results may vary with specific equipment.