I am a complete newcomer to medium format so bear with me. I've only shot medium format once as a project in school with my professor's Pentax 67. I just purchased my first medium format camera, a Mamiyaflex C2 with 135 F/4.5 (it hasn't even arrived in the mail yet). Being very excited to start shooting with it, I've been doing as much research as possible on this camera and the Mamiya C TLR line. One thing I came across was the availability of single exposure backs for these cameras. This lets these cameras use 2-1/4"x3-1/4" cut film or glass plates if I understand correctly. My question is: Why? Is it because of the slightly larger negative size? It doesn't seem very reasonable to give up the convenience of roll film for a marginally larger negative. If that is what one is after, wouldn't you just use a 4x5 camera? Although, the first thing I thought of when I saw those backs was the possibility of pocket-size tintypes. That might actually be pretty cool.