Equipment Used for Motion Pictures
P.M. Abbott · The Annals of the American Academy of Political and Social Science · 1926
motion picture film consists of a series of photographs, each three-fourths of an inch high and one inch wide, taken and projected at the rate of about sixteen per second, and enlarged on the screen to nine by twelve feet, or more. This means high speed and a magnification of one hundred and forty-four diameters and upwards, or more than twenty thousand times. The slightest imperfection or flaw at any stage of this complicated process spells failure. It is only natural, then, that the-highest type of precision machinery, representing an enormous investment, be required in every branch of the industry. It divides, roughly, into (1) machinery used in the manufacture of the raw film; (2) machinery used in the studio where the pictures are made; (3) equipment in the laboratory, where the prints, or duplicate copies, are made; (4) equipment in the exchange, from which the prints are distributed to theatres; and (5) equipment in the theatre, where the pictures are shown to the public. The first step, raw film manufacture, can be dismissed in one paragraph, for the reason that it requires little equipment not common to all photographic manufacture. Motion picture film is manufactured in the same precise way, and with the same apparatus, as ordinary photographic film. It is then cut to a width of one and three-eighths inches and perforated along both edges with four sprocket holes to each frame or picture. These sprocket holes are for the purpose of engaging the film with the teeth of the sprockets, which feed it through camera, printer and projector. The perforating machine must be accurate to one ten thousandth of an inch, for the slightest lack of steadiness in the film will be magnified enormously on the screen.