A recent thread here asked about IQ issues on a 7D, and some of the discussion linked back to Merklinger's article on the Luminous Landscape (http://www.luminous-landscape.com/reviews/cameras/50d.shtml). To paraphrase, the pixel density of a 50D equates to 39 MP if extended to full frame. He concludes that image defects in his early tests were due entirely to the higher spatial resolution, and disappeared once the image was downsampled to more normal size. The 7D's pixel pitch of 232 px/mm works out even higher, 46 MP if full frame. Can this be right? P&S cameras with plastic gum drops (presumably, figuratively, and comparatively) for lenses have pixel densities ranging from mid-30 to 43 MP/cm^2. By comparison, the 5D2, 7D, and 50D have densities of 2.4, 5.4, and 4.5 MP/cm^2, respectively. If Merklinger's 24-105/4L is not sufficiently sharp for even the 50D's sparsely spaced pixels, how are the $100 consumer cameras able to capture any image at all? Does it seem reasonable that a P&S houses the sharpest lenses made? Also worthy of comment, HM goes on to say the 50D's pixel pitch makes the sensor diffraction limited at f/7.5, giving the relationship as N=1600/pixelpitch in millimeters. The 7D's 232 px/mm predicts diffraction softened images at smaller than f/6.9. Again in stark contrast, the P&S with 43 MP/cm^2 works out to 655 px/mm, making them essentially pinholes at smaller than f/2.4. (I guess that answers the first part!) Comments or thoughts?