I've been reading up on this and I'm seeing people suggest anywhere from 50mm lenses to 70-200mm lenses and in between. It appears most say 50mm is the way to go. My question is this. I find myself having to back up a lot in order to get more of a subjects body in the picture. I can only imagine what I'd have to do with a 70mm shot. Are people suggesting the bigger lenses because they have larger studio space?