Choosing Sheet Film
Medium and large format cameras use sheet film supplied in various pack sizes. You load this film into a film back that slides into the rear of the camera. Each film holder usually accommodates two sheets of film. Some cameras accept different size film backs, allowing you to change the aspect ratio of your photos simply by changing the camera back.
What Is Sheet Film?
Today's large format cameras are direct descendants of old-fashioned cameras used by the pioneers of photography, except that they use negative type film instead of glass plates coated with light-sensitive emulsions. Because sheet film is sensitive to light, you must load it in a darkroom. Film manufacturers place notches along the top edges of the film so you know which way the emulsion faces, and so you can identify the type of film. After exposure, you remove the film and develop it using various chemicals.
Some medium-format cameras use instant film. Also supplied in sheets, this film contains development chemicals that activate once you take the photograph. While it's not capable of the same reproduction quality, you can view and share photos instantly.
Film Speed and Grain
There's an indirect relationship between the sensitivity of sheet film and its grain size. Film with a low ISO or ASA rating has fine grain, is best for capturing small details, and has better color reproduction. Photographers use this kind of film for portraits and landscapes. Film with a high ISO rating, known as fast film, has more grain, but is more suitable for action photographs. Typically, the ISO/ASA speed rating of sheet film varies between 25 and 400.
There are two types of black and white film: orthochromatic and panchromatic.
Orthochromatic film has high sensitivity to blue and green colors, and is less sensitive to orange and red shades. The low sensitivity to red means you can confidently develop this film using a red safelight, although it may be necessary to use color filters to correctly capture tones. Panchromatic film has an even response to all colors, but as with color film, you can't use any form of light when removing or developing it. Sheet film and roll film use similar technology.
If you're using color film, you have a choice between color negative and color positive. Color negative film, like black and white negatives, has inverted colors, a feature that aids printing and makes it easier to develop and process. Color positive film produces slides and transparencies, which is why movie film is color positive.
Popular Sheet Film Sizes
Although there's a wide range of sheet film sizes, the most popular medium and large format film sizes include:
- Medium format sheets based on the 120-roll film size
- Medium format 4 x 5 film
- Large format 5 x 7 film
- Large format 8 x 10 film
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