4When the back is attached to the camera, no attention need be paid as to whether the filmor the shutter has been previously wound.The film/shutter crank, which normally winds the shutter and the film simultaneously,automatically performs only the required function. For example, if the shutter is woundand if the film in position has been exposed, turning the crank will only advance the filmto a fresh unexposed section. Also, when the back is on the camera, the dark slide mustbe completely withdrawn before an exposure can be made.Exclusive Lenses and Automatic DiaphragmNikkor and Zenzanon lenses are especially designed for Bronica cameras and can be usedwith not only the S2A but also other earlier models (S type, S2 type and C type). You canspeedily adjust the focus of the bright image. These lenses (Nikkor 40mm, Nikkor 50mm,Nikkor 75mm, Nikkor 105mm, Nikkor 200mm, Zenzanon 100mm, Zenzanon 150mmand Zenzanon 300mm) have instant reopening automatic diaphragms.Depth-of-Field Preview ButtonBy pressing this depth-of-field preview button, you can check the depth-of-field beforeexposing.Selector for 12 or 24 ExposuresOrdinary 120 film gives 12 exposures, 24 exposures are possible on the 220 size film.The Bronica S2A has an entirely new system permitting either film to be used.