Movies for TV - Early Television Foundation

FILM TRANSMISSION EQUIPMENT 121
diffusing the light to the dark areas and preventing sharp focus.
Strange as it may seem, one or two deep scratches are much less
detrimental than the multitude of small scratches produced by the
methods mentioned above. Never handle the lens elements and keep
fingers off the lenses.
If the film channels are not kept clean, little mounds of hard
emulsion scraped off the film by its passage through the projector
begin to build up. Often called horns, these can ruin a new film in
one projection by causing deep scratches.