Medium and 35mm Film Formats

Film Formats (35mm, Medium Format)

35mm: While Leitz wasn't the first to use 35mm movie film in still-film cameras, the Leica made it popular and standardized the 24mm x 36mm frame size. The Leica used 35mm motion picture film, doubling the 35mm movie frame size (24mm x 18mm), which is still used in some "half-frame" cameras such as the Olympus Pen F. Some early Nikon, Minolta, and other Japanese rangefinders adopted the 24mm x 32mm frame size (aka "Japanese size") which fits into a 8x10 sheet of photo paper more readily, but didn't catch on.

The 35mm film cartridge that we know actually took a while to become standard. It was first introduced in 1934 with the Nagel Retina, which became the Kodak Retina. Up to then, each manufacturer had a proprietary cartridge, which was often reloadable. The Kodak 35mm cartridge was designed to be one-use (although reloadables have existed since the beginning), which made more profit for Kodak.

35mm film is also called 135 film because that was the number Kodak assigned it. The standard 24mm x 36mm frame uses 864 sq. mm of film surface.

120 film: Kodak numbered all of its film types, starting with 100 (I think). So 120 roll film is actually a rather early format. It was used in the Kodak Brownie cameras. The film is 60mm wide and comes on a reusable plastic spool with an opaque black paper backing. This is because unlike 35mm film, 120 film does not come in a light-tight cartridge.

Unlike 35mm film too, 120 film has no standard size. There are a variety of framing options that manufacturers have used:

Compared to 35mm, medium format uses 3~4 times as much film surface. This allows for better tonality (smoother gradations), finer detail, and less apparent grain. The downside is that medium format cameras are bigger, heavier, more expensive, darker lenses (f/2.8 or f/4 is usually the largest aperture), and film-developing costs more.

220 film: This film was a response to the complaint that 120 film only could take between 10-16 shots/roll for the standard frame sizes. 220 film doubles the length of 120 film and allows 20-32 shots/roll by doing away with the black paper backing. Instead, there is a small paper leader and tail attached. Some argue this makes 220 film more susceptible to light leakage and film scratches but in practice, I have not found a difference.

However, 220 film is twice expensive as 120 film and developing it commercially usually costs twice as much. So there is no price advantage. And to its disadvantage, the number of film types available in 220 film is much less than 120 film. The main users are/were wedding photographers, who needed to take many photos in a sequence. With wedding photographers going digital, 220 film may be headed to its graveyard.

Medium Format vs. 35mm Lens Equivalents

Photographers new to medium format often want to know what the equivalent lens would be on a 35mm camera. As you might know, the larger the film frame size, the larger your lens has to be to get the equivalent "angle of view" or amount of coverage. So while a 50mm lens is considered standard by many for the 35mm format, with a 6x7 camera you would most likely use a 90mm lens.

Equivalencies are made difficult because frame ratios are different. 35mm format is rather elongated with a 3:2 ration (36mm : 24mm). On the other hand, 6x6 is square, 6x7 fits nicely onto 4x5 paper, and 6x9 is the closest to the "golden ratio."

When calculating equivalencies, should you use the width of the film in proportion? Landscape photographers would most likely use this because they are shooting predominantly in landscape format and don't use the height of the frame as much. However, other photographers might use the diagonal of the frame as a good compromise between horizontal and vertical angle of coverage.

I've calculated some rough numbers as a guide.

Wide Angle Lenses

Standard Lenses

Telephoto/Portrait Lenses

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