Mamiya 645

The Mamiya 645 camera systems are a series of medium format film and digital cameras and lenses manufactured by Mamiya and its successors. They are called "645" because they use the nominal 6 cm x 4.5 cm film size from 120 roll film. They came in three major generations: first-generation manual-focus film cameras, second-generation manual-focus film cameras, and autofocus film/digital cameras.
Mamiya 645 Manual Focus System.
Mamiya 645 manual focus cameras.
All seven of the manual-focus Mamiya 645 cameras can use the same lenses and film inserts (film spools). The two generations use different viewfinders, grips, and other accessories that are not always cross-compatible.
Mamiya 645 Manual-Focus Lenses.
The Mamiya 645 Manual-Focus lenses will work on all manual-focus bodies. They will also work on autofocus bodies such as the Mamiya 645AF, Mamiya 645DF and Phase One 645DF, but manual-focus lenses will require light metering after the lens has been stopped down, unlike native autofocus lenses. Third-party adapters exist to use these manual-focus lenses on Nikon F mount, Canon EF mount, and other cameras. These lenses will not work on the Phase One XF unless modified. All Mamiya 645 lenses are multi-coated. Nearly all have curved aperture blades, rendering smooth backgrounds at wider aperture settings.
The internal shutter in the first-generation 645 bodies only supported flash synchronization at 1/60th of a second. This made outdoors fill flash difficult, and so some lenses were equipped with a built-in leaf shutter which supported flash synchronization at all speeds up to 1/500th of a second. Leaf shutter lenses had a separate PC socket. In order to take advantage of the faster speeds the internal shutter had to be fired at 1/30th of a second or slower.
Mamiya 645 Autofocus System.
The Mamiya 645 Autofocus (AF) system was launched in 1999 with the 645AF. It was a departure from the previous manual system, in that the finders and grips were no longer detachable and interchangeable. It still used the same lens mount, but the new autofocus lenses did not have an aperture ring; rather, the lens aperture was controlled by dials on the camera. Manual-focus lenses could still be used on the autofocus cameras, but not vice versa. If manual focus lenses are used, the lens aperture must be set before metering the scene (known as "stop-down metering") which made the manual-focus lenses of limited usefulness compared to the newer autofocus lenses.
Mamiya 645 Autofocus Lenses.
Lens abbreviations.
Some Mamiya 645 AF lenses are also sold as Phase One lenses. Phase One also sells Schneider-Kreuznach lenses, which are also branded as Mamiya. See the history of Mamiya for more information.