Процесс проявки цветной пленки C-41

Color film developing process

C 41 is a chromogenic color print film developing process introduced by Kodak in 1972, superseding the C 22 process. C 41, also known as CN 16 by Fuji, CNK 4 by Konica, and AP 70 by AGFA, is the most popular film process in use, with most, if not all photofinishing labs devoting at least one machine to this development process. Processed C 41 negatives, as with all color films, consist of an image formed of dye. Due to the long term instability of dyes, C 41 negatives can fade or color shift over time. This was a significant problem with early films; whether the newer films are archival or not is a subject of some debate.

C 41 film consists of an acetate or polyester film base, onto which multiple emulsions are coated. Each layer is only sensitive to a certain color of visible light. In an idealized, illustrative example, there are three light sensitive layers: one is red sensitive, another is green sensitive, and the top is blue sensitive. Beneath the blue layer is a yellow filter, composed of dyes or colloidal silver, also known as Carey Lea Silver. All silver based photographic emulsions have some sensitivity to blue light, regardless of what other colors they may be sensitized for. This filter layer serves to remove the blue light, which would expose the layers beneath it. Beneath the blue sensitive layer and the yellow filter are the green and red sensitive layers.

After processing, the resulting film is a negative, meaning that the darkest spots on the film are those areas that were brightest in the source. Light is projected through the finished negative onto color photographic paper, yielding positive image prints. Nearly all C 41 films also include an orange mask to offset the optical inadequacies of the dyes in the film. These C 41 negatives appear orange when viewed directly, though the orange base is compensated for in the formulation of color print materials. Some C 41 films, intended for scanning, do not have this orange base.

It is also possible to cross process slide film for the E 6 process in C 41, which yields negatives with a color shift and stronger saturation. Varying brands and film speeds yield different color shifts producing bright, saturated colors and high contrast. C 41 film also may be processed in E 6, yielding positive images with a strong green cast, caused by the orange mask. C 41 film can be processed in standard black and white chemicals, to produce a monochrome negative image. The negatives will typically be of very low contrast, and cloudy, partly caused by the orange mask.

While C 41 is usually considered a color process, Ilford currently manufactures a "chromogenic" C 41 compatible black and white film, XP2 Super.