Medium format

Glossary Terms

Medium format refers to roll-film cameras whose image formats are larger than 35mm film (often significantly so). Top quality medium-format SLRs like the Hasselblad or TLRs like the Rolleiflex were the workhorses of professional photography until digital photography displaced them. The term medium format almost always implies 120 film, although 220 (double the length of 120) and 620 (essentially 120 on a skinnier spool) would also qualify. In contrast, large format implies a camera designed for sheet film of 4×5" or larger.

The width of all these films is about 62 mm; but by convention this is rounded off to "6" (centimeters) in referring to the different images sizes that are possible. Medium-format image dimensions are determined by the camera, and not by the film itself. That is to say, a roll of 120 film could be used to expose images of 6x4.5cm, 6x6, 6x7, 6x9 or even 6x12 cm depending on the camera.

Because of medium format's greater image area, additional detail and smoother tones may be recorded when compared to 35mm. This is true even when the camera is a rather inexpensive model, such as a basic TLR or folding camera. As such, medium format may be a surprisingly affordable method for photographers to improve the technical quality of their film images.The larger image area also implies higher costs for film and processing, but some find this a useful discipline encouraging a more deliberate approach to photography.

120 and 620 are rollfilms using paper backing to protect them from exposure to light, and should be loaded in subdued light conditions. In simpler cameras, a red window is used to view rows of frame numbers corresponding to different image sizes, printed onto the backing paper. 120 and 620 are nearly identical except in the spools, and it is quite possible to re-spool 120 film onto a recycled 620 spool, if only the smaller spool size will fit in a particular camera. 220 film is much like 120 except instead of a paper backing, it has a paper leader. Omitting the paper backing behind the film itself permits double the usual number of exposures to be wound up onto the same spool size used for 120.

Type 116 or 616 film was a paper-backed film 70mm wide—no longer made, although it persisted longer than many early-20th-century rollfilm sizes. Some might also consider this medium format.

The term "medium format" continues to be used in the context of professional digital cameras, particularly for digital backs made to be compatible with medium-format film camera systems. However sensor chips are typically limited to smaller dimensions than traditional medium-format film images: A typical high-end digital camera system might use a CCD of about 33×44 mm in size.