Is That Lens Sharp In The Corners? No? Are You Sure? | Dennis A. Mook
Often I hear photographers and reviewers remarking that a certain lens is not sharp in the corners. But is it really not sharp? Or maybe what you are seeing is the result of a curved field lens being tested against a flat subject. I wrote about curved field lenses versus flat field lenses with some illustrations on the difference here.. If you are interested, please follow the link and read it.Here is a practical example of what I mean. The image above was made using the highly touted Fujifilm 23mm f/1.4 XF lens. The lens is very sharp, even wide open and contains an aspherical element. I used it to demonstrate that, looking at the image above, one may wrongly conclude that the lens is not sharp in the corners……
Source: www.thewanderinglensman.com