Rather than using hollowed-out metal plates, photo-typesetting machines use strips of photographic film to carry images of the text that will be printed. The photo-typesetting machine produces images on fresh, unexposed film. Conventional phototypesetters can expose up to 50 characters per second, but usually expose closer to 30 characters per second. Phototypesetting does not use hot metal. Instead, type is set by exposing a light-sensitive material (film or paper) to light projected through a character negative. A computer controls timing.
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