The reason you want a rotating back on the RB is for the Waist Level Finder, or ground glass, that most people use. Its a royal pain to use the finder sideways. You can get a prism, but then it weighs a TON, and still not ergonomic. The camera needs to be, and was indented to be, used vertically. I would just pony up for an RB kit. its a great camera.
Originally Posted by frobozz