David, have you heard anything about vignetting problems with Canon EF lenses on the new EOS 5D, particularly at FL<50mm? This is anecdotal stuff from another forum, apparently originating in Europe where the 5D is already being sold. (And no , it's not from our buddy "Mr. Anonymous" this time.)
I would expect a more pronounced vignetting effect with extreme wide angles, which is the case with nearly all full-frame digital sensors, but not a 50mm lens. I will wait with an open mind and see what the 5D does when I get mine for testing.
Hardly anything really new that comes out that someone somewhere isn't on the web with all kinds of strange depreciative stories, and few of them turn out to have any substance. To me it is on a par with the BS you hear any time a bunch of men get together who have too much time on their hands.