Transactions of the Society of Motion Picture Engineers (1922)

Record Details:

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ample, in the first attempt to get more pictures per second than I had therefore made, the heavy spring belt take-up, which had been satisfactory at 50,000 exposure per minute, did not wind up the film at all at 100,000 per minute, for the reason that the belt made a circuit around the pulley it was supposed to drive without touching the pulley at all, centrifugal force holding it entirely clear of the pulley. We put a cord inside the spring belt to kill the force at the end of the tangent and have had no further trouble from that source. At higher rates direct drive and friction plates would doubtless be needed. Incidentally, new hazards were discovered in attempts to mechanicall}^ handle film at 100 feet per second. In first trials some old out-of-date stock was used and the camera door was left open so that the action could be watched. As the last end of the film passed 1 ^^^^^K^^^H| w ■ i-^ ^^^1^ 1 « ■'^\ li ^'Ti-ra ■ ■ i Fig. 1 — First model motor-driven camera producing 1,600 exposures per second on Standard Film. around the sprocket, a piece about 1^ inches long was snapped off and, flying in my direction, cut a severe gash in my bare arm, though I was seventeen feet away. Always there is found in the receiving magazine quite a quantity of bits of film, for the end frays out like the cracker of a whip before the motor can be stopped. Tension of any kind is out of the question. The best result so far has been attained by guiding the film in a narrow channel made of very dense wood, grainless, and having an oily feel. Resistance seemed to develop as the cube of the speed. One horse power is required to drive the camera; a ^ horse-power motor will not bring the instrument up to speed. There is but one pair of gears in the camera. These things are mentioned only to show that very little of past experience in motion picture photography is of much benefit in attempts to handle 100 feet of film per second in a camera. 70