Film Formats Explained: 35mm, 120 Medium Format, Large Format and Instant

Film format describes the size of the film and the size of the frame a camera exposes on it. Bigger formats record more detail and less visible grain at a given print size, at the cost of bigger cameras, fewer frames and more expensive film. Here are the formats in common use today and what each is good for.

35mm (135 film)

35mm film is 35mm wide with sprocket holes down both edges, wound into a light-tight metal cassette. Its official name is 135. The standard frame is 24x36mm, and rolls come in 24 or 36 exposures. It is the most widely available format, the cheapest per frame to buy and process, and the cameras are compact, fast to use and plentiful.

Half-frame cameras, like the Olympus Pen series, expose an 18x24mm frame on the same film, doubling the frames per roll. Panoramic 35mm cameras such as the Hasselblad XPan expose 24x65mm frames across the sprocket area.

120 medium format

120 film is about 61mm wide, with no sprocket holes, wound on a spool with a paper backing that keeps it light-tight. The frame height is always roughly 56mm; the camera decides the width, and that determines the number of frames per roll:

Format	Approx. image size	Frames per 120 roll	Typical cameras
6x4.5 (645)	56 x 42mm	15 or 16	Mamiya 645, Pentax 645, Fuji GA645
6x6	56 x 56mm	12	Hasselblad V, Rolleiflex, Yashica TLRs, Bronica SQ
6x7	56 x 70mm	10	Pentax 67, Mamiya RB67 and RZ67, Mamiya 7
6x8	56 x 76mm	9	Fuji GX680
6x9	56 x 84mm	8	Fuji GW690, folding cameras
6x12, 6x17	56 x 112mm, 56 x 168mm	6, 4	Panoramic cameras and roll film backs

A 6x7 negative has close to four and a half times the area of a 35mm frame, which shows as smoother tones and finer grain in a large print. 220 film, twice as long as 120 with no backing paper along most of its length, has been discontinued.

Large format sheet film

Large format cameras take individual sheets of film, loaded in darkness into double-sided film holders. The common sizes are 4x5 inches and 8x10 inches, with 5x7, 11x14 and larger "ultra large format" sizes still made in small batches. Each sheet is exposed and can be developed individually, which makes large format ideal for the Zone System.

A 4x5 negative has roughly 15 times the area of 35mm; an 8x10 negative is usually contact printed rather than enlarged. Large format cameras also allow movements that control perspective and the plane of focus.

Instant film

Instant film develops itself. Integral films, such as Polaroid i-Type, 600 and SX-70 and Fujifilm Instax Mini, Square and Wide, carry the chemistry in a pod at the bottom of each frame, spread by rollers as the picture is ejected. Peel-apart films separate a negative from a positive print after development. Each frame is a single unique print, which is the appeal and the limitation.

Other and historic formats

Older roll film sizes such as 127, 620 and 116 turn up in vintage cameras. 127 is still made in small runs, and 620 cameras can usually take 120 film respooled onto 620 spools. 110 cartridge film, with its tiny 13x17mm frame, is made again by Lomography. Motion picture film in 35mm is the source of stocks like Cinestill, while 16mm and Super 8 are for cine cameras.

Choosing a format

35mm if you want speed, portability, low cost per frame and the widest choice of film.
Medium format if you want noticeably better tonality and detail and can live with 8 to 16 frames per roll.
Large format if you work slowly, often on a tripod, and want maximum quality and control over each exposure.
Instant if you want a finished print in the moment.