The original camera negative (OCN) is the film in a traditional film-based movie camera which captures the original image. This is the film from which all other copies will be made. It is known as raw stock prior to exposure.

The size of a roll varies depending on the film gauge and whether or not a new roll, re-can, or short end was used. One hundred or 400 foot rolls are common in 16mm, while 400 or 1,000 foot (ft) rolls are used in 35mm work. While these are the most common sizes, other lengths such as 200, 800, or 1,200 ft may be commercially available from film stock manufacturers, usually by special order. Rolls of 100 and 200 ft are generally wound on spools for daylight-loading, while longer lengths are only wound around a plastic core. Core-wound stock has no exposure protection outside its packaging, and therefore must be loaded into a camera magazine within a darkroom or changing bag/tent in order to prevent the film being fogged.