Film format refers the size and shape of a single frame of film. The most common format today is the familiar 35 mm film. A single frame of this film is 24 mm wide by 36 mm long. This gives an aspect ratio -- the ratio of length to width -- of exactly 1.5, and any enlargement done without cropping will have this ratio. For example, a 35 mm frame fits very neatly into a 4" x 6" print, but won't fit neatly on an 8" x 10" piece of paper. To print the full 35 mm frame on 8" x 10" paper will give a print area 6 2/3" x 10" with empty stripes down the long sides. In other words, the film frame is skinnier than the 8" x 10" paper. If you want to fill the entire 8" x 10" paper with a photo, some cropping will necessarily occur at one end or the other, or both.
Although 35 mm film has become ubiquitous through custom, there is no reason that film must be cut to this size. There are cameras that take larger sizes of film (and a few that take smaller). One advantage of using larger film is clear: to get a print of a given size, less enlargement is necessary when starting with a larger negative. This means a sharper print with smaller grain.
There is a family of cameras that use film that yields an image 6 cm along one edge of the frame. This film comes in rolls but without the sprocket holes of 35 mm film. This film format is called medium format. The 6 cm edge of the image is across the width of the roll of film; the other edge of the frame can be anything the camera designers want it to be. Common lengths of the frame are 4.5 cm, 6 cm, 7 cm, 8 cm, and 9 cm.
Even larger negatives are possible using large format cameras. Common frame sizes are 4" x 5" and 8" x 10"; less common sizes are 5" x 7" and 11" x 14". (Imagine a piece of film 11" x 14"!) Film in these sizes comes in precut sheets rather than on a roll. The fact that the film comes in individual sheets gives rise to another advantage enjoyed by large format photographers: each sheet can be processed individually to overdevelop or underdevelop as the particular image warrants without affecting any other shots. These cameras tend to be bulky and cumbersome to use, but give awesome results. And it wasn't so long ago that they were considered the norm and not so cumbersome at all.... You know those old movies where the press photographers are carrying big boxy cameras with flash bulbs in circular reflectors? Those are 4" x 5" cameras!
As a v...e...r...y general rule of thumb, 35 mm cameras are best where fast action and light weight are at a premium. This format also benefits from the widest selection of lenses and the lowest price of equipment and film. Large format cameras are most commonly used for carefully controlled studio shoots or exquisite quality nature images. Medium format is a compromise between these two extremes, often prized by wedding and portrait photographers.
Timothy Edberg / 6511 Homestake Dr. South / Bowie, MD
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