alamak.. are we talking abt the quality of the pix or are we juz slapping nos??
i'm merely suggesting a decent 3rd party alternative for both canon n nikon. far more productive to just get that instead of fussing over which system has better choice of UWA, blah blah blah.
quality wise, largely up to the photog, isn't it? unless we are talking about defective equipment here. tokina seems to be decent from online reviews, including CS users' feedback so i shall assume someone wondering whether to get canon or nikon will NOT be "hampered" by the lens.
if one is damn experienced pro who can bring the best out of canon/nikon's high end lenses, then diff story, but such a person would be answering questions instead of asking them