Motion Blur

Introduction

Motion blur is normally relevant to a film camera - when a frame of the film captures an object that is moving too fast (or the camera is moving too fast), that particular frame is exposed too long to light to '"freeze" the motion of that object and so appears blurry on that frame of film. The amount of motion blur can be controlled in a film camera in two ways:

• by changing the frames per second (fps) of the film so that each frame is exposed for a shorter period of time to the light, thus freezing more and more the action in place. The typical film fps rate is 24fps but can be increased to 60fps or more which will diminish the motion blur and make the movie look more "choppy" - this is usually done for special effects in fast moving action scenes.

• by adapting the angle of the opening in the so called rotary shutter of the film camera. A smaller angle will expose the light for a shorter period of time which will diminish the motion blur. See below for an example of how a rotary shutter works.

Photo camera shutter vs film camera shutter (rotary shutter)