valokuvafilmiä

Valokuvafilmi, often referred to as photographic film or simply film, is a transparent strip or sheet material coated on one side with a gelatin emulsion containing light-sensitive silver halide crystals. When exposed to light, these crystals undergo a chemical change, forming a latent image that can then be developed into a visible photograph.

Historically, film was a primary medium for capturing images in photography and cinematography. It consists of several layers: a base, typically made of cellulose triacetate or polyester; an adhesive layer; the emulsion layer where the image is recorded; and a protective overcoat. The sensitivity of the film to light is measured by its ISO speed, with higher numbers indicating greater sensitivity and the ability to capture images in lower light conditions. Different types of film exist, including black-and-white, color negative, color reversal (slide), and specialized films like infrared.

The process of developing film involves a series of chemical baths that convert the latent image into a permanent photograph. For color negative film, this results in a negative image where colors and tones are inverted, requiring printing onto photographic paper to produce a positive image. Color reversal film, on the other hand, directly produces a positive image, often referred to as a slide or transparency.

While digital photography has largely supplanted film for many applications, film remains in use by enthusiasts, artists, and in some specialized professional fields due to its unique aesthetic qualities, dynamic range, and archival properties. The tactile nature of handling film and the distinctive look of film-based images continue to hold appeal for many photographers.