I am sure the majority of us know that 50mm lenses are among the best corrected lenses for optical aberrations. I have a single coated, early 70's, 50mm Nikon lens that is as sharp as I wanted it to be. I admit I have not cared about the corners so I do not really know how good it is wide open and honestly I could not care less. I seldom use it wide open and most of the time I am at f5.6 or beyond.

Before this lens I had a Nikon 50mm f1.8 that was also very sharp and once again I never tested the lens for its resolution in the corners. Till now I have enlarged images to 12x18 inches from my lenses and the corners never bothered me. I certainly believe that modern lenses are very sharp due to the advances in optics and coatings. My old 50mm lens cannot be pointed at a source of light because flare is simply horrific, result of a single coating. Even the sharpest lens means nothing without good shooting techniques and the rule of stopping the lens down about three apertures from wide open still applies to most lenses. If depth of field is not important that f5.6 will render the sharpest images but if f16 is what we need that will be the aperture we should use and the results most probably will be the same regarding sharpness. As we close the lens to its smaller apertures diffraction takes place but nothing that at least in my case will make me feel it will spoil my images.

Tripods and VR are making lenses better than ever...IF we use good techniques when shooting.

Ken Rockwell did his testing of various Nikon 50mm lenses in 2006 using a Nikon D200 10.2 megapixel camera. The camera is an antique by today's standards. The lenses were mostly old designs even then. I own three of the lenses he tested, and they're decent lenses, but I don't think that the ancient camera is good enough to discern subtle differences you might see in a more modern camera. Furthermore, none of the lenses tested would likely hold up against more modern designs on a high megapixel camera, maybe at their optimum apertures, but certainly not wide open or nearly wide open.

I respect him for his knowledge of equipment and history. I always read his reviews of new cameras and lenses and find them to be informative. One of the things he admitted to me personally is that he just doesn't have time to go back and clean up his web site of all of the old and obsolete (useless) stuff. (I questioned him on a digital versus film article in which he compared the results from a 6 megapixel digital camera with those of a 4x5 film camera.) He has gotten somewhat better in going back to insert comments into some old reviews to point out that something better has come along. Not in this case.

I have been shooting in the highest f/stop ranges, f/22 to f/32 and getting everything in focus for years now. I know I get some slight softness in the details from diffraction, but that is completely correctible with sharpening programs I have in Photoshop to correct the softness. I have an action that can even revive a slightly blurry image and make it tack sharp.

So why should I worry about gaining an insignificant amount of acuity in an image at the sacrifice of getting the whole subject in focus?