That is likely because of the large difference in resolution. The screen test involves showing the image at 1 image pixel per screen pixel, so the D8xx image is much larger. In other results I've seen, scaling the D8xx image down to the same resolution as D6xx images brings the results into line. (FWIW, I own a D600 with the new shutter, and am evaluating a D810, and find the overall image quality on the D810 an improvement. Perhaps not what I wanted, as it means I may decide to buy it:-)) -- David
I recall reading somewhere that the results are normalized (to a 8MPix image), exactly to prevent what you're describing.