fotofilm

Fotofilm, or photographic film, is a thin transparent base coated with a light-sensitive emulsion used in analog photography to capture images. The base, often cellulose acetate or polyester, is coated with silver halide crystals suspended in gelatin. When irradiated by light in a camera, the crystals form a latent image that is revealed by chemical development, producing a negative or color image on film.

Film comes in several formats. 35mm (135) film is the most common, packaged in cartridges that hold 24 or 36 exposures. Medium-format film, such as 120, yields larger frames (for example 6×6 cm, 6×7 cm, 6×9 cm). Large-format film exists on sheets (4×5 in, 5×7 in, etc.). Color films use multiple emulsion layers and dye couplers to render color; black-and-white films record luminance with silver halide.

Exposure is governed by film speed, expressed as ISO. Higher ISO increases sensitivity but can add grain. After shooting, film is processed in chemical baths: black-and-white typically develops in developer, then stop bath and fixer; color negative in C-41; color reversal (slide) in E-6. The resulting images may be printed in a darkroom or scanned for digital viewing.

Although largely supplanted by digital photography, fotofilm remains in use among enthusiasts for its aesthetic and archival properties. Modern film stock is produced by several manufacturers worldwide, and surviving labs offer processing and scanning services.