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What is the features common to all films?

Sizes and packings

The widest range of color and black and white emulsions is made in 35 mm (135) size. Originally meant as movie film but adopted by photographers for its convenience and quality, 35 mm film is supplied in cassettes giving up to 36 exposures of standard 24×36mm format. A few 35mm films are available as 15m and 30m (or 50ft and 100 ft) lengths in tins.

This bulk film is for cameras with special film backs, or you can cut it into short lengths to refill regular-size reloadable cassettes. Doing reloads reduces film costs but risks scratches and dust. It is generally a false economy for professional work. Medium format film, usually called ‘120’, is rolled in the opaque backing paper on a spool and is 62 mm wide. The number of pictures per film depends on your camera’s picture format. ‘220’ film is on a thinner base, allowing twice the length and number of pictures on the same spool size as 120 but this is declining in popularity as it is more vulnerable to damage.

Sheet films packed 10, 25, or 50 per box come in several standard sizes such as 4 × 5 inch and 8×10inch The edge-notching helps you locate the emulsion surface when loading film holders in the dark, and has a shape code by which you can ‘feel’ film type, as well as identify it after processing. Roll films have a farther type and batch identification data printed along their edges. Check the manufacturer’s data sheet for the product to decode information.

Instant print sheet materials are mostly used as 8- or 10-exposure packs 31⁄4×41⁄4inch and 4×5inch, or individual sheets 4×5inch and 8×10inch special envelopes. They are of two main types, ‘peel apart’ and ‘integral’. Each exposure on peel-apart material is removed from

the camera as a sandwich of two sheets you leave together for a timed period, and then peel to reveal a right-reading print on one sheet.

It is most often used in a pack holder which attaches to 120 cameras with magazine backs, or 35 mm cameras with removable backs. Sheet instant film slots into a special film holder inserted into a view camera which also contains the roller mechanism used for squeezing out the chemical gel used when processing. These peel-apart materials are still extensively used by professional photographers in the studio to produce a quick print confirming lighting, exposure, composition, etc. You have to remember though that colors may not exactly match your final results on conventional color film. ‘Integral’ instant picture prints eject from the camera after exposure as a plain card which forms a picture as you watch.

Its main use is in Polaroid point-and-shoot cameras which are designed with an internal mirror – otherwise, pictures on integral material are reversed from left to right. However, Polaroid announced in 2008 that it would cease manufacturing instant film products and so they are hard to come by now although Fuji instant films are still available.

For APS cameras films are 24 mm wide and come in cartridges that open and self-load when dropped into the camera body. The picture format is 17×30mm, but cropped by the camera at the shooting stage. There are 15, 25, or 40 exposures per cartridge, and the film is returned from the lab with its processed negatives secured inside the container which is not designed to be opened.

Mechanized printing machinery retrieves the film automatically for reprints, etc. Hand printing is possible, but you will have to break the cartridge open. APS never really caught on with professional photographers as they found the film is too small, it just 56% of 35 mm and the point-and-shoot amateur camera market was soon dominated by digital cameras. Kodak, who introduced the format in 1996 ceased producing APS cameras in 2004 although it is possible still to buy a limited range of APS films.

Other formats are rarely encountered but the industry manufactures them for specialized applications, often in science and industry. For example, astronomers occasionally require extremely flat negatives, much more dimensionally stable than acetate film and so still use old-style glass plates although CCD arrays are now more commonly used.

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