Photographic film

Photographic film is a sheet of plastic (polyester or celluloid) coated with an emulsion containing a light-sensitive chemical such as silver nitrate. Other modern light-sensitive layers consist of silver halide salts with variable crystal size that determine the sensitivity of the film. When the emulsion is subjected to controlled exposure to light (or other forms of electromagnetic radiation such as X-rays), it forms a latent image. Chemical processes can then be applied to the film to create a visible image.

Depending on the type of film this image is transparent and can be framed to become a slide, which is viewed with a slide projector or viewer, or a negative. This process is called film developing. A negative is used to produce a photographic print (one or more copies as desired). Slides, negatives and prints are stable when exposed to further light for viewing.

Instant photography uses a special type of camera and film that automates and integrates developing and printing, without the need of further equipment or chemicals. This process is carried out photo-by-photo, as opposed to the regular system, where the exposure of a whole film is finished before developing.

Black-and-white photographic film uses one layer of silver, whereas colour film uses a three-layer dye-based structure.

Because photographic film was ubiquitous in the production of motion pictures, or movies, these are also known as films.

The first transparent photographic film was made by Eastman Kodak in 1885. Roll film, allowing several images without opening the camera, was introduced by Kodak in 1895. See also film formats. Prior to this, glass photographic plates were required, which were far more expensive and cumbersome, albeit also of better quality.

Companies that manufacture photographic film:

• Agfa
• Efke
• Foma
• Forte
• Ferrania
• Fujifilm
• Ilford
• Imation (3m)
• Kodak
• Konica
• Lucky
• Maco
• Orwo
• Polaroid
• Svema
• Tasma

See also: Timeline of photography technology