You cannot open the camera's film door until the film is completely rewound into the film cassette. Once the film is developed, it is not cut into strips and sleeved like 35 mm film, but is instead returned enclosed in its original cartridge. The system helps in this regard by providing an index print - a regular size print that contains tiny, digitized thumbnail images of each frame on the roll of film. A number on the film cartridge is matched to an identical number on the index print. A storage case for negative cartridges is available.
Users can exchange rolls as often as they like.
This handy feature allows photographers to shoot the same scene using two or more different types of film, without having to waste any exposures. A normal lens for an APS camera is 40 mm as compared with a 50 mm lens for the normal lens of a 35 mm camera. Simply multiply the size of the APS lens by 1.25 to arrive at the equivalent focal length for a 35 mm lens having the same angle of view. Note that photo processing cost will vary based on the sizes. Although the magnetic coating is on the entire film surface, cameras and photofinishing equipment read and write data in very narrow tracks outside the image area, near the edge of the film.