Filmstock consists of a transparent celluloid, polyester, or other plastic base coated with an emulsion containing light-sensitive chemicals. Cellulose nitrate was the first type of film base used to record motion pictures, but due to its flammability was eventually replaced by safer materials. Stock widths and the film format for images on the reel have had a rich history, though most large commercial films are still shot on (and distributed to theaters) as 35 mm prints.
Originally moving picture film was shot at various speeds using hand-cranked cameras; then the speed for mechanized cameras and projectors was standardized at 16 frames per second, which was faster than much existing hand-cranked footage. A new standard speed, 24 frames per second, came with the introduction of sound. Improvements since the late 19th century include the mechanization of cameras, allowing them to record at a consistent speed, the invention of more sophisticated filmstocks and lenses, allowing directors to film in increasingly dim conditions, and the development of synchronized sound, allowing sound to be recorded at exactly the same speed as its corresponding action. The soundtrack can be recorded separately from shooting the film, but for live-action pictures many parts of the soundtrack are usually recorded simultaneously.
As a medium, film is not limited to motion pictures, since the technology developed as the basis for photography. It can be used to present a progressive sequence of still images in the form of a slideshow. Film has also been incorporated into multimedia presentations, and often has importance as primary historical documentation. However, historic films have problems in terms of preservation and storage, and the motion picture industry is exploring many alternatives. Most movies on cellulose nitrate base have been copied onto modern safety films. Some studios save three B&W negatives exposed through red, green, and blue filters. Digital methods have also been used to restore and preserve films. Film preservation of decaying film stock is a matter of concern to both film historians and archivists, and to companies interested in preserving their existing products in order to make them available to future generations (and thereby increase revenue).
Some films in recent decades have been recorded using analog video technology similar to that used in television production. Modern digital video cameras and digital projectors are gaining ground as well. These approaches are extremely beneficial to moviemakers, especially because footage can be evaluated and edited without waiting for the film stock to be processed. Yet the migration is gradual, and as of 2005 most major motion pictures are still recorded on film.
Contributed by: Mohinder Pal Singh
Date: March 15, 2010