Film stock

There are several variables in classifying stocks; in practice, one orders raw stock by a code number.

A piece of film consists of a light-sensitive emulsion applied to a tough, transparent base. Around 1955, film manufacturers substituted a cellulose triacetate plastic base for cellulose nitrate. The old stocks are sometimes called nitrate and the new ones are sometimes called safety film.

Film chemistry may produce either a positive or negative image. Camera films that produce a positive image are known as reversal films. But since negative films are much more commonly used, there are terms based on the steps needed to produce a viewable finished print; one speaks of negatives and positives. Obviously there are color and black and white stocks.

Film is also classified according to its width and the arrangement of its sprocket holes--a range of gauges from 8mm to 70mm or more, single-perf or double-perf configurations.

Another critical property of a stock is its film speed, or sensitivity to light. Speed determines the range of lighting conditions under which the film can be shot, and is related to granularity[?] and contrast, which influence the look of the image.

Finally, one should mention the distinction between camera stocks and print stocks. It is possible to transfer video images to film stocks that can be developed and printed in the normal manner. Theater performances have been preserved that way for many years--the 1964 New York production of Hamlet with Richard Burton, for example, was shot on video and printed as a film that was released in movie theaters. Digital video equipment has made this approach easier, and certain movies such as Timecode (2000) have been produced that way.

See also Film format

Links:

• Kodak's history of film stock (http://www.kodak.com/US/en/motion/about/chrono1.shtml) - note: emphasis on Kodak products