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Polaroid instant slide film and
associated processing systems give easy access to several finished and
ready-to-use slide films without the necessity of a darkroom or
commercial processing. The system is comprised of five different 35mm
films and manual or motorized "instant" processing and slide-mounting
equipment.
The film itself is loaded in the camera, exposed, and rewound like any
other 35mm film. Each Polaroid instant cartridge is supplied with its
own sealed plastic container of processing chemicals that Polaroid has
dubbed its "processing pack." After film is exposed in almost any 35mm
camera, it is loaded into the auto processor and in a minute or two is
ready for visual inspection. A few minutes more to mount the slides in
an easy-to-operate slide mounter and you are ready to project or print
the finished images.
The color film is different from most other conventional emulsions in
that it is based on the additive color principle rather than normal
subtractive color alignment of other color slide films. Polachrome CS
contains a microscopically fine lined additive color screen consisting
of a repeating pattern of red, green, and blue color filters at about
1000 color triplets per inch, with each triplet comprising a single
red, green, and blue filter element.
Over the filters is a very thin color screen protective layer and over
that a positive image-receiving layer. It is in this layer that the
final silver image will be deposited. Four additional layers are
situated above the receiving layer. They consist of a protective layer
directly above, which also functions as a stabilizer, a release layer
that allows upper film layers to be removed during processing. Below
the top antihalation layer is a panchromatic silver-halide emulsion
layer.
A color image is formed almost in the same way as is a color television
picture. Microscopic examination of the white portions of a finished
Polachrome CS slide reveal equal amounts of red, green, and blue. One
of the problems associated with the use of an additive color screen is
that the base density of the film tends to be much higher than that of
conventional slide material. Because of its higher density, measured at
0.7 compared to conventional slide films at 0.2, the brightness of
Polachrome is considerably less. This brightness differential is most
noticeable in the highlight areas (the toe of the characteristic curve)
and least in the midtones (straight-line portion of the curve) plus
shadow areas (shoulder of the curve).
Since image formation of the four black-and-white films takes place
without an additive color screen, their base densities are very similar
to regular black-and-white emulsions.
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