The Mamiya M645j is a great entry level camera into the world of medium format photography. This camera was first produced in 1975 as an affordable system for those who did not want to pay the price of a Hasselblad. It is also considerably smaller and lighter than its high end cousins. There are limitations to this system that we will get to later.
The camera body has a three lug bayonet lens mounting chassis that accepts Sekor C lenses which range from 45mm to over 200mm in length, including a wide variety such as shift lenses for architecture, leaf shutter lenses, and so on. The shutter is depressed by a button down and to the right of the lens mount on the same front face of the body and also features an exposure safety lock mechanism preventing accidental firing of the shutter, which I am sorry to say is easy to do. The shutter button has the standard remote cable screw mount for cable release. However air bulb releases with the larger fittings do not fit with the wider lenses (45,55mm etc.). The thinner cable release fittings fit along side the wide lenses with ease. Normal to telephoto lenses, no problem.
Moving right around the camera, the shutter speed dial has settings from 1 second to 1/500 of a second and 'B'/bulb for timed exposures. X-sync speed is 1/60th of a second. And there is a vivitar style sync plug for flash synchronization when not employing a hot shoe.
The back of the camera opens to receive film chargers and uses 120 and 220 sized roll film. There is also a place to put notes or the film box end to keep track of the film you are using.
Further on, the film is advanced by a film winder crank that is located opposite the shutter speed dial. The exposure counter is also located on this side of the camera. 'S' is the position of the counter when a fresh film charger is inserted and as the photographer winds on the counter moves up to '1'for the first exposure. A roll of 120 roll film will render 15 exposures and a roll of 220 film will render 30 (220 roll film is basically 120 roll film without the paper backing which allows more film to fit onto the spool.) This camera also has a multiple exposure switch on the same side as the winder and the photographer can easily change between modes.
The bottom of the camera has a standard 1/4'x20 thread tripod mount and to very small cylindrical notches to either side that is typical of Mamiya MF cameras of the time and with Mamiya tripod adapters these notches aid in camera stability by further anchoring the camera to the tripod when inclining the camera to the side.
The top of the camera body has the viewing screen of which there are about five different focusing models available. There is also the battery test button. Press the button on the right and the green light lights up on the left to indicate battery power. Many different types of viewrs can be attached to this camera. Waist level finders. Standard prisms. Metering prisms. Hot shoe mounts. You name it, it can be found.
This cameras shortcomings are few but it does have them. You cannot change film backs in the middle of a roll as the film is mounted onto film chargers that actually fit inside the camera for light tight conditions. It does not have a mirror lock up feature. But the affordability and mobility of this camera far outweigh its perceived faults.