One year ago, I made my calculations and guessed on the 645D sensor size. Some people did disagree much at my Blog and also elsewhere on the net, but now it is proven today that I did guess right and correctly for the exact figures, 100% correct! =Victory= :-DJust see the official announcement that has just been published:-http://www.camera-pentax.jp/new/news05/index.html (645D Product Preview