These types of camera are often called roll film cameras and take 120 or 220 roll film. This refers to the format of film used in the camera, and it also differs from 35mm film in that the film is wound up between a length of black paper and it is this that protects the film from exposure to light, not the light tight cassette as with 35mm. The leader that pulls the film onto the take up spool is in fact the paper and as there is also a trailer of paper that protects the exposed film, very little film is wasted at both ends of the emulsion.

Where as 35mm film is usually in only one format 24mm x36mm (or occasionally as half frame 24mm x 18mm), 120 film is used across a wider variety of formats and as the length of film is standard, the number of frames is determined by the size of the format of the camera format.

The width of the film is always the same at 6cm or 2 1/4 inches, and it is the measurement down the length of the film that changes depending upon the camera format used.