John Seaman , May 21, 2012; 03:37 p.m.
The top of the camera is pretty conventional, the lever around the rewind handle is the battery check. The lens mount is FL, the predecessor of FD, but the breech lock fitting is the same so it can be used on FD cameras.
It can operate as an automatic lens, or in preset mode by turning the second ring to stop down the aperture to the value preset on the first ring. I read somewhere that the f1.2 lenses were made for the Canon Pellix, which needed a high aperture lens to brighten up the viewfinder and make up for the light lost by the half silvered fixed mirror.
The Top of the FT