Quote Originally Posted by thekingb
I don't understand why it's a "waste." What is wasted?




I can't speak for Jordan or you, of course, but for me personally, it is money and sharpness that is wasted.





Quote Originally Posted by thekingb
Certainly not center sharpness, as nice L glass on an APS-C body takes advantage of a great lens' center sharpness and can all but eliminate corner softness and vignetting issues.




What you are saying is the same thing that 99% of photographers believe, and it is repeated by many magazines, web sites, forums, and probably even books on photography. So by taking that position you definitely have a lot of good company.





However, it is completely wrong.





And it's especially untrue in the case of the 17-40. Even the $100 kit lens is sharper. This urban legend persists because of two common flaws in the method used to compare different format sizes: using different iris diameters and different magnifications. These factors must be equalized between sensor sizes to provide any sort of useful comparison baseline, and when that is done, it becomes clear that larger sensors are sharper (usually by even more than you would expect based on the lens price differential).
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