Does anybody know the difference between Mamiya M645 AE Prism finder N (introduced with 645 Super) and M645 AE Prism Finder (introduced with Pro)?? According to Mamiya's website, N type is usable with Pro and above as well as Super. The former has a squarish appearance and the latter has rounded corners. Other than that, they look identical. I am using N type finder with Pro body and it works just fine. Am I missing any new feature intordued in the later model??