What is shutter angle and how does it influence motion blur in film?

What is shutter angle and how does it influence motion blur in film?

• A. The arc of the shutter; larger angles create more motion blur, smaller angles reduce it.
• B. The arc of the shutter; smaller angles create more motion blur, larger angles reduce it.
• C. The arc of the shutter; shutter angle has no effect on motion blur.
• D. The arc of the shutter; shutter angle only affects exposure, not blur.

Answer: (A)

Shutter angle is the arc of the shutter’s opening during each frame, which sets how long the image is exposed. A larger shutter angle means the shutter stays open longer, so moving subjects have more time to move while the frame is being captured, producing more motion blur. A smaller angle shortens that exposure time, so motion is captured more crisply with less blur. This also affects brightness, since longer openings let in more light and shorter openings reduce light, so filmmakers balance blur and exposure when choosing the angle. For example, at 24 frames per second, a typical 180-degree shutter exposes the frame for about 1/48 second, while a 90-degree shutter is about 1/96 second, and a 360-degree shutter exposes for about 1/24 second, increasing motion blur.