Production Glossary
Photographic Film
Photographic film is a piece of cellulose acetate, polyester, or nitrocellulose that is spread with a combination of two un-mixable liquids, also known as an emulsion. The emulsion is composed of silver halide salts, a combination of elements that are sensitive to light. These salts, which vary in size, establish the resolution, disparity, and sensitivity of the film. Exposure of the film to light creates an invisible picture. Color film employs three or more color-sensitive layers of silver salts that osmose the dyes, making the salts more susceptible to picking up the colors. Black-and-white film only require one layer of silver halide salts to create an image.The earliest photographic technique was a daguerreotype, which did not use film at all. The images produced with this process were developed on a brass or silver plated copper plate.
The groundwork of photographic film was laid by Vero Charles Driffield and Ferdinand Hurter and their investigation of how light sensitivity applies to film. The company responsible for creating the inaugural flexible photographic film (which was spread on paper) was Eastman Kodak in 1885. A few years later, in 1889, the well-known translucent, plastic film debuted. Trials with color film and photography occurred in 1861, but the process was not available for consumers until the 1930s.
The three primary forms of photographic film are: black-and-white reversal film, print film, and color reversal film. Although it exists, black-and-white reversal film is rare. More commonly black-and-white negative film is reverse processed to achieve the same effect. Print film manifests a negative which transposes the colors in the image. To be properly displayed, the film must pass through a lens, or be in close proximity to direct light. Color reversal film creates a transparency to be displayed with a projector. These transparencies are also known as slides.
In addition to the basic forms of film, a few unique film types exist. The Poloroid, an instant photographic process, eliminates the need for additional chemicals or equipment. Films that capture infrared radiation and UV images, as well as X-ray radiation are used regularly in specialized fields and require particular equipment to operate.
