Here are some Dxo marks, my main question is what glass will go on a FF Sony? Has is got to be a special lens for FF or will they all fit? I might could swing for the 850 at the discount price and pick up the glass later. But as you can see there really isn't much difference in the three DXO marks. If glass is going to cost me out the a$$ I had rather stick with the 580.I also read where Sony actually made Nikon sensors
http://www.dxomark.com/index.php/Cam.../(brand3)/Sony