The term roll film is usually reserved for film wound up on a spool with an interleaving light-tight backing paper to protect the wound-up film. The spool is loaded into the camera in daylight, the backing paper leader threaded to a second spool, and the film wound from picture to picture once the camera is closed. This is the classical roll film of roll-film cameras. Common current film widths are 62 mm and 45 mm. The rear of the backing paper carries sets of consecutive numbers spaced at frame intervals for different image formats. In some roll-film cameras these numbers ...(100 of 19384 words)