35mm: What is 135 format or 35mm film?
135 or 35mm film is the most common photographic film format. The film is 35mm wide, and each standard image is 24×36mm. Individual rolls of 35mm film are enclosed in single-spooled light-tight metal canisters. This allows cameras to be loaded even in broad daylight. The end of the film is cut on one side to form a leader so that it is easy for the film to be inserted into a corresponding slot in the camera’s take-up spool.
135 format film comes in both positive and negative, black and white, color, and infrared. Color negative 35mm film can be processed at a drugstore or one-hour lab. 35mm black and white, color slide, and infrared films must be processed at a professional lab.