Much of the color film used in the Navy is manufactured by Eastman Kodak Company. Kodak markets color films for both professional and amateur photographers. Color films intended for use primarily by professionals are identified by the word professional in the name; for example, Kodak Vericolor III Professional Film, Type S (VPS).

Both professional and amateur films have similar color quality, sharpness, and granularity characteristics. Also, they have emulsions made up of many different chemicals that tend to change slowly with time. Starting from the day they are made, all color films begin to change; and as the films age, their color balance changes.

Amateur films are manufactured to age and reach a peak color balance much later than professional films. The manufacturer allows for the time amateur film will be in storage, on the store shelf, and in the camera before it is developed. The ISO speed assigned is adequate for calculating exposure for normal picture-taking situations.

Professional films are manufactured so they are very near their optimum color balance at the time they are shipped from the factory. These films should be kept refrigerated or frozen until shortly before use. Refrigeration keeps film near the optimum point until used and provides the photographer with confidence in consistent results. Precise film speeds are provided for professional films. The film is intended for prompt processing to prevent any significant shift in color balance after exposure.

If you require optimum color balance and precise film speed within about 1/6 f/stop professional film is appropriate for your work; however, when you intend to be away from home base for an extended period of time without refrigerated storage or processing facilities, amateur film should be your choice.

Instant Picture Film

Currently, the only manufacturer of instant picture film is Polaroid. There are two basic types of instant picture film: peel apart and integral. After exposure and removal from the camera, peel-apart film must be timed while the film develops. After it has developed for the specified period of time, the negative backing is peeled away and discarded. Integral films develop outside the camera and have no negative backing to be removed.

Instant picture color films are tripack materials with built-in processing. Peel-apart film uses a system whereby the exposed silver halides develop to a metallic silver negative. When no metallic silver is present, dyes pass to form the color image. Integral films use a reversal process in which the areas of unexposed silver halides are the locations where the dyes are produced to form the positive image.

Instant picture film is a very useful medium in an imaging facility, particularly when still electronic technology is not available. Instant picture film is used commonly for identification and passport photographs, but it is also valuable in determining test exposures. Before you make your final exposures on conventional film, a Polaroid photograph can be taken to confirm composition, lighting, and exposure.

FILM SIZES

There are two types of film formats used commonly in photography. They are roll film and sheet film. Both formats come in a variety of sizes.

Roll Film

All roll film is packaged so the film can be loaded and unloaded from a camera in daylight. Number 120 film has a paper backing that prevents the film from being exposed in daylight; 35mm film is wound in a lighttight cassette that prevents the film from being exposed by ambient light.

Figure 2-5. Notch codes used to identify the type of film.

Figure 2-6. Location of notch code that indicates the emulsion is toward you.

The most popular medium-size format film is No. 120. This film, depending on the camera format, provides negatives that are 6x6 cm (2 1/4 x 2 1/4

inches), 4.5x6 cm, or 6x7 cm. No. 220 roll film is used for making the same size negatives, but because most of the paper backing is eliminated, the roll is longer than a 120 roll and provides twice as many frames as 120 film.

Still picture 35mm films come prepackaged in cassettes in lengths for producing 12, 20, 24, and 36 frames per roll. Also, 35mm films come in rolls 100 feet long that can be bulk-loaded into reusable cassettes.

Sheet Film

Sheet or cut film is made in a variety of sizes from 4x5 to 11x14 inches and larger. The most common sizes are 4x5 and 8x10 inches. Most sheet film has no paper backing and must be loaded into and removed from film

holders in the darkroom in total darkness or under the appropriate safelight. Eastman Kodak does market the Kodak Readyload Packets that provide two sheets of film in a paper packet. These packets can be loaded into a Kodak Readyload Packet film holder or a Polaroid film holder, Model 545. The Kodak Readyload Packets are available only in 4x5 format.

Most sheet films have reference notches in one edge of the film. In the dark, this allows identification of the film type and the emulsion side of the film. Every film type has a different notch code (fig. 2-5). The emulsion side of the film is toward you when the notches are along the top edge in the upper right-hand corner, or on the bottom right edge in the lower right-hand corner of the film (fig. 2-6).

For those sheet films that do not have notches, the emulsion side of the film can be identified under a safelight. The emulsion side is lighter in color than the base side. If the emulsion side of the film must be identified in total darkness, wet your lips and place the edge of the film between them. The emulsion side of the film will stick to one of your moistened lips.