Sensor & film sizes.
In perspective.

04 / From strip to picture

The film and the photograph
have different dimensions.

A film name may refer to a cartridge, a roll, a rounded image format, or a sheet. Compare the exposed image area when you want to compare capture formats.

35 mm and half frame

Standard 135 still photography exposes roughly 36 × 24 mm on a strip that is 35 mm wide. Half-frame cameras use a smaller picture on that same strip; the Pentax 17 example is 24 × 17 mm. The strip width is not the image height.

120 is a roll designation

It does not mean 120 mm wide. The camera’s film gate determines whether the roll records 645, 6×6, 6×7, 6×9 or a panorama. Those centimetre-based names are rounded: the Pentax 645NII image is 56 × 41.5 mm, not 60 × 45 mm.

Sheet sizes need a separate treatment

“4 × 5 inches” converts to a nominal envelope of 127 × 101.6 mm. Actual film is cut slightly smaller to fit the holder, and the holder masks the edges. This guide shows nominal envelopes with an explicit label; it does not pass them off as exact exposed areas or calculate a photographic crop factor from them.

Instant film has a border

An instax mini picture is 62 × 46 mm when rotated to landscape, inside an 86 × 54 mm sheet. The comparison uses the picture area. With a hybrid camera or printer, this output size tells you nothing about the digital sensor used to make the image.