Тypes of polaroid films
Polaroid or instant film is a type of film used for instant cameras. This particular type of film itself contains chemicals needed to develop and fix the photo that is being exposed and developed within the camera, minutes after being shot.
Polaroid film and cameras was introduced in 1960s. Early technology was based on the process of the film being pulled through the rollers which opened the pod containing reagent. Rollers spread it between the exposed negative and positive sheet. The length of this process was depending on the film type and temperature. By the end of the process, developed photo sheet is peel away from the negative.
Integral Polaroid film that automatically developed and fixed the photo without intervention from the photographer was introduced in 1972.
Instant positive film works basically like this: positive film which later produces the picture, due to the diffusion transfer, has ability to move dyes from the negative to the positive throughout the reagent. Process varies from film to film, getting more sophisticated and complex.
Variety of film sizes goes from 24mm x 36 mm up to 50.8 cm x 61 cm. The most wide spread is 83mm x 108 mm size. At first film was distributed in rolls, but today it is packed in 8-10 sheet packages.
Black and white film is the least complex one. After being produced and exposed inside the camera, squeezed against the positive sheet. Unexposed silver halide grains from the negative sheet are solubilized by the reagent, and transferred to the positive.
40-Series Land Picture Rolls (3 1/4″ x 4 1/4″) were the first instant films, presented in 1940s. Each roll produced eight b/w prints, and required additional Polaroid Land 40 back.
Subtractive color film is based on the layers of emulsion and dye layers. The negative carries three emulsion layers sensitive to the primary colors. Each of it also contains a layer of developing dye of the complementary color beneath itself. Once the negative is exposed by the light, the reagent enables the developing dye to transfer form negative to positive sheet surface. Layers of emulsion are being exposed to their respective color, and then started blocking the complementary dye beneath it, reproducing the original color.
Integral film process is similar to subtractive color instant film, but improved by the ability of the film to integrate all the layers, while being exposed, developed and fixed. The image itself is fixed in the plastic envelope, commonly associated with Polaroid.
Some of the first color films were developed by the Polaroid Company in 1960s, also as a part of a 40-series that will later evolve into famous Polacolor.
Additive film is based on the color mask of transparent red, green, and blue lines. Emulsion layer of black and white, reproduces the color images in transparency film. The eye easily blends the primary colors together, to form the correct color.
After the Polaroid withdrawn all of their instant photography products from the market in 2008, the gap was successfully filled by the products by Fuji and Impossible project companies, fitting the most of the Polaroid cameras.