Because so many modern video enthusiasts and filmmakers are self taught, it’s not uncommon to run across a few that don’t know what the 180 degree shutter rule is, or why they should even care about it. So what is it? The rule states that your shutter speed needs to be one over two times your frame rate. In this video by Stronz Vanderploeg, he explains a lot about the rule and give you visual evidence as to why he endorses it. “When it comes to video cameras, there are 3 ways to control exposure internally on the camera: ISO, Aperture, and Shutter Speed/Angle. ISO affects noise performance, Aperture controls depth of field and Shutter Speed determines motion blur. All too often I see videos shot at different shutter speeds with varying amount of motion blur but is there really such a thing as ‘the right way to do it?'”

From Wikipedia:

“A rotary disc shutter is a type of shutter. It is notably used in motion picture cameras. Rotary discs are semicircular mirrors that rotate in front of the film gate, and thus expose the film. As the mirror spins it reflects the image onto the ground glass so that it can be viewed by the camera operator part of the time. The other part of the time the mirror allows the light to pass onto the film. On simple cameras this shutter is fixed and usually semi-circular. On more advanced cameras the shape of the shutter can be adjusted. This shutter setting is referred to as the shutter angle.

Adjusting the shutter angle controls the proportion of time that the film is exposed to light during each frame interval. The angle of the shutter forms a proportion to the time that each frame of film is exposed.”

[Via Filmmakers]