Chauncey, the Mercury II was a significant upgrade, and allowed the use of regular 35 mm cassettes, as we use today. The camera really seems like a great user, maybe the smoothest shutter among my many 35 mm cameras. I've owned several Leicas (none at the moment) and I like the operation of the Mercury as well,as any of the Leicas. Too bad it doesn't have interchangeable lenses. Bernard, the format is determined by the shape of the opening at the film plane, and the Mercury is designed to be a half-frame 35 mm camera. If I want landscape format I have to turn the camera 90 degrees, but it will still be half-frame. In order to get a pano photo I have to take, say, 4 overlapping shots and combine them. Marty