Motion picture photography (1927)

MOTION PICTURE PHOTOGRAPHY activities usually demand action which is rapid and flawless. This makes it difficult for the novice to duplicate actions of which he has only grasped the general scope. By slowing the action he is enabled to analyze the actions and to appreciate the component parts of such action to such a degree that he can soon learn to duplicate them. So important has this work become that many cinematographers now specialize in high speed (Slow motion) cinematography. As ordinarily shown, motion pictures are taken and projected at the rate of sixteen pictures per second, but for the scientific investigator the rate of speed may vary from as high as 30,000 to the second in the study of high speed phenomena to as slow as one exposure per hour or even one exposure per day, as used in studies in the change of structural materials, or the growth of a plant. All of these may be projected at normal speed for screen study or each frame may be subjected to individual scrutiny under the magnifying glass in special cases as in seeking to eliminate lost motions in machine assembly, etc. Reduced to normal projection speed, bullets swim across the screen like leisurely fish and bursting shells separate like a group of mosquito wrigglers. Many high speed processes, such as the flow of steam ; air and gases ; combustion and explosions; automobile engines; the action of governors; the synchronism of electric generators ; the flow of water in turbines and water wheels ; the action of steel and wood-working machinery; and machine tools; etc, may be photographed at high speed and slowed down in projection so that they may be studied with the greatest accuracy. 24