photographic film
nounA flexible strip coated with a light-sensitive emulsion that records an image as a pattern of developed silver or dye.
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Structure A flexible transparent base coated with a light-sensitive emulsion, in which exposure to light forms an invisible latent image that development renders visible and permanent.
→ Photographic emulsion -
Formats Film classified by gauge — its width in millimeters (8, 16, 35, 65 mm) — together with its perforations and frame size, which set resolution, cost, and the equipment required.
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Process Film distinguished by process: negative stock, from which positive prints are struck, versus reversal stock, which yields a positive directly.
Branches
- film speed A measure of a photographic emulsion's sensitivity to light, expressed on the ISO scale, that sets how much exposure the film requires to record a usable image.
- film gauge The width of a strip of photographic film, measured in millimeters, and by extension the format defined by that width together with its perforations and frame dimensions.
- color film Photographic film that records the colors of a scene as well as its brightness, most commonly by stacking three emulsion layers sensitized to blue, green, and red light.
Photographic film is the first, literal sense of film: a thin light-sensitive layer on a flexible support. It is a thin film (its etymological root) put to work as a recording medium, and for a century it was the physical basis of nearly every motion picture.
Structure
From the surface down, a film is a stack of thin layers: a supercoat that protects against scratches; the emulsion, where the image is actually recorded; a subbing layer that bonds emulsion to base; the base, a transparent flexible support of cellulose triacetate or polyester; and an anti-halation backing that absorbs light which would otherwise reflect off the back of the base and halo bright highlights.
How it records an image
Exposure does not produce a visible image. Where light strikes a silver-halide crystal it reduces a few silver ions to metallic silver, leaving an invisible latent image — a handful of silver atoms per exposed grain. Chemical development then amplifies this by a factor of millions, converting entire exposed grains to silver while leaving unexposed grains untouched; fixing removes the remaining light-sensitive halide so the image is stable in light. The chemistry lives one level down, in the emulsion.
Formats
Film is described by gauge — its width — which trades cost against image quality: 8 mm and Super 8 for amateur and small-format work, 16 mm for documentary and television, 35 mm as the long-standing theatrical standard, and 65/70 mm for large-format spectacle. Perforation shape, frame size, and whether the stock is negative or reversal further define it.
The digital successor
Since the 2010s most production records onto a digital image sensor rather than film. The sensor is the electronic counterpart of the emulsion: where emulsion stores an image chemically in silver, a sensor stores it as electrical charge in a grid of photosites. Photographic film persists as an aesthetic choice, an archival medium, and the origin of the vocabulary digital capture still uses.
See also
- photographic emulsion— The light-sensitive layer of film: microscopic silver-halide crystals suspended in gelatin, in which exposure forms a latent image.
- image sensor— The electronic component that captures a digital image, converting light into electrical charge at a grid of photosites — the digital counterpart to photographic emulsion.
- thin layer— The word's oldest sense: a thin coating or membrane of a substance — the literal meaning from which “film” as a recording medium descends.
Sources
- Mees & James, “The Theory of the Photographic Process” (4th ed.)
- Kodak, “Essential Reference Guide for Filmmakers”
Last revised: September 18, 2026