Of course you can see - if you on the screen (at 1: 1) searches - optical loss at the corners, but that is relevant for each very ambitious amateur photographers not work in practice. The differences in landscaping comparison shots eg 50mm (at 300) with the very good Nikon AF-S Nikkor 50mm 1: 1.4 g Lens (with optimal aperture 8.0), on a picture (for example) are 20 x 15cm not visible.
In retrospect, I have invested a lot of time in the Lens Testergenisse on universally known homepages, which are certainly technically correct, but that is in many cases criticism at the highest level and in practice for most of no importance.
Nikon knows very well why "the market" for Nikon lenses always paid a slightly higher price. The brand alone is - over a longer period - for a higher price not!
D800 with Nikon AF-S 28-300mm: Christmas sharp, low light, without flash, slow shutter speeds ... and ... great pictures. As often formulated: "Looking at the pictures amazement is often difficult to conceal :-)!"
