I am considering buying an R7, and I want to know what 50mm f/2 Summicron would take best advantage of the camera's functionality. Would it be an E55, a Leitz Canada 3-cam, or a ROM lens? To clarify, I want a lens that will take advantage of what the R7 can do, but not one that has features the camera will NOT support, so e.g. if a ROM lens will do this or that but the camera will not then I don't want to pay extra for a ROM lens when a plain old 3-cam would do the trick.