ANALYZING A MOVIE

Analyzing a Movie

Analyzing a Movie

Cinematography is the technique and art of making motion pictures, which are a sequence of photographs of a single subject that are taken over time and then projected in the same sequence to create an illusion of motion. Each image of a moving object is slightly different from the preceding one. Projector Motion-picture projector projects the sequence of picture frames contained on a ribbon of film, in their proper order.

A claw engages perforations in the film and pulls the film down into the film gate, placing each new frame in exactly the same position as the preceding one. When the frame is in position, it is projected onto the screen by illuminating it with a beam of light. The period of time between the projection of each still image when no image is projected is normally not noticed by the viewer. Two perceptual phenomena--persistence of vision and the critical flicker frequency--cause a continuous image. Persistence of a vision is the ability of the viewer to retain or in some way remember the impression of an image after it has been withdrawn from view.

The critical flicker frequency is the minimum rate of interruption of the projected light beam that will not cause the motion picture to appear to flicker. A frequency above about 48 interruptions a second will eliminate flicker. Camera Like a still camera (see CAMERA), a movie camera shoots each picture individually. The movie camera, however, must also move the film precisely and control the shutter, keeping the amount of light reaching the film nearly constant from frame to frame. The shutter of a movie camera is essentially a circular plate rotated by an electric motor.

An opening in the plate exposes the film frame only after the film has been positioned and has come to rest. The plate itself continues to rotate smoothly. Photographic materials must be manufactured with great precision. The perforations, or holes in the film, must be precisely positioned. The pitch--the distance from one hole to another--must be maintained by correct film storage. By the late 1920s, a sound-on-film system of synchronous SOUND RECORDING was developed and gained widespread popularity. In this process, the sound is recorded separately on a machine synchronized with the picture camera. Unlike the picture portion of the film, the sound portion is recorded and played back continuously rather than in intermittent motion.

Although editing still makes use of perforated film for flexibility, a more modern technique uses conventional magnetic tape for original recording and synchronizes the recording to the picture electronically (see TAPE RECORDER). If the number of photographs projected per unit time (frame rate) differs from the number produced per unit time by the camera, an apparent speeding up or slowing down of the normal rate is created. Changes in the frame rates are used occasionally for comic effect or motion analysis. Cinematography becomes an art when the filmmaker attempts to make moving images that relate directly to human perception, provide visual ...