Movies for TV ([1950])

CHAPTER MOVIE-MAKING EQUIPMENT CAMERAS A movie camera consists essentially of a holder for unexposed film, 1 a device for moving it past the lens and stopping it momentarily while the exposure is made, a shutter to prevent light from reach- ing the film when an exposure is not being made, and a take-up reel for rewinding the exposed film. In other words, it is merely I an adaptation of the still camera already known to most readers. !By reason of its specialized application, the movie camera re- quires a number of refinements which make it somewhat more ' elaborate than the definition above might indicate. The sequence of operations is performed by either turning a handle or provid- ing a motor drive of some kind. For normal film making a motor 1 drive is used to ensure that film is moved at a constant speed through the camera. Hand-turned drives almost always vary in i speed due to the impossibility of maintaining a constant torque. I Two forms of motor drive are in general use: these are spring and | electric motors. Most of the cheaper and more popular makes of semi-pro- | fessional or amateur cameras are provided with a spring drive which is built into the body of the camera. One winding of the spring may be sufficient to expose about twenty-five feet of film i at twenty-four frames a second, but, of course, this differs for each make of camera. As a general rule, spring drives are not too sat- 47