FILM PLATFORM: How Projectors Work

What is a

A projector is any device which creates a light-projected image by shining a light through a small, transparent image. In order to refine this image, projectors must also employ lenses in order to focus the light. Projectors can transform a very small image into a large one because the image which is projected will be the same size as the pool of light created by the light source behind the transparent image.

There are many different kinds of projectors, but they work on the same basic principle. One of the more complicated of the commonly known projectors is the movie projector.

The modern movie projector evolved out of the slide projector. A slide projector focuses, projects and enlarges an image which is made from a photograph. In order to be projected, these images have to be rendered in a transparent format onto various forms of clear plastic, such as nitrocelluloid. The slide projector moves these individual images into a precise location in front of the projector light and behind the lens(es).

A movie projector works on a similar principle, but in this case, the individual photos are strung together on one extremely long piece of film. This film is wound around a spool and the projector contains a motorized unit which winds the film from one spool to another. In between spools, the film is stretched between the light and lenses and projected onto a large, white screen. The screen is white in order to provide the images with an opaque quality, just as photographs are printed on white paper.

No form of moving image projection or animation really utilizes true moving images. Instead, single, non-moving photos or illustrations depict objects or people in various progressive, chronological states of movement.

As the human eye processes visual data, each image entering the brain is retained for a brief period of time. This phenomenon is referred to in the theory of "persistence of vision." As a film projector moves through a reel of film, it pauses for a tiny fraction of a second at each image, but this amount of time is actually less than the amount of time that it takes for the human brain to move from one image to the next. This means that the eye and brain can't distinguish between the visual data of actual moving objects and the visual data of the still film images, so the images appear to be moving.