The illusion of films is based on the optical phenomena known as persistence of vision and the phi phenomenon. The first of these causes the brain to retain images cast upon the retina of the eye for a fraction of a second beyond their disappearance from the field of sight, while the latter creates apparent movement between images when they succeed one another rapidly. There would be no true motion pictures, however, until live action could be photographed spontaneously and simultaneously. This required a reduction in exposure time from the hour or so necessary for the pioneer photographic processes to the one-hundredth (and, ultimately, one-thousandth) of a second achieved in 1870. It also required the development of the technology of series photography by the British American photographer Eadweard Muybridge between 1872 and 1877. The French physiologist Étienne-Jules Marey took the first series photographs with a single instrument in 1882; once again the impetus was the analysis of motion too rapid for perception by the human eye. Marey invented the chronophotographic gun, a camera shaped like a rifle that recorded 12 successive photographs per second, in order to study the movement of birds in flight. In 1887 in Newark, New Jersey, an Episcopalian minister named Hannibal Goodwin developed the idea of using celluloid as a base for photographic emulsions. The inventor and industrialist, who had earlier experimented with sensitized paper rolls for still photography, began manufacturing celluloid roll film in 1889 at his plant in Rochester, New York. Such a device was created by French-born inventor Louis Le Prince in the late 1880s. He shot several short films in Leeds, England, in 1888, and the following year he began using the newly invented celluloid film. Thomas Edison invented the phonograph in 1877, and it quickly became the most popular home-entertainment device of the century. Seeking to provide a visual accompaniment to the phonograph, Edison commissioned Dickson, a young laboratory assistant, to invent a motion-picture camera in 1888. Building upon the work of Muybridge and Marey, Dickson combined the two final essentials of motion-picture recording and viewing technology. These were a device, adapted from the escapement mechanism of a clock, to ensure the intermittent but regular motion of the film strip through the camera and a regularly perforated celluloid film strip to ensure precise synchronization between the film strip and the shutter. Dickson’s camera, the Kinetograph, initially imprinted up to 50 feet (15 meters) of celluloid film at the rate of about 40 frames per second.
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