You know what's funny..? If you use a 17-40 L lens on a film body, the same thing will happen too.. LOL.. Digital is however a little different, being that the sensor doesn't have the ability to allow light hit it from every angle like film does.. but, as far as the lens is conserned, if it is soft in the corners of a full frame digital body, it will be that same in a film body too.. which is not a real issue to me.. Think about it,... Before.....( I believe it was 1995)... Canon introduced the 17-35mm f2.8 L lens, which replaced their darn good 20-35mm f2.8 L lens.. and it took how long for Nikon to come out with a 17-35 of their own,...and just look at the size of that thing.. it is big and bulky,..hmmmmmm......could it have anything to do with that anchient lens mount..??

YES! ..and guess why they won't ever come out with a FF camera..?