The Canon VT was a 35mm film camera released in 1956 that accepted interchangeable lenses with a screw lens mount. It used a Rangefinder for manual focusing and a cloth Focal-Plane Shutter with shutter speeds from 1 sec...
Since the first Canon camera came out in 1946, there have been a total of eight (8) different mainstream lens mounts used. Of course, every time, you change major specs on a lens mount, existing lenses cannot be used on...