Having just added a 5D to my collection, I've been looking around at better wide angle glass, specifically the Nik 14-24 f2.8 which everyone seems to love.
(I'm aware I'll lose loads of functions but manual focusing isn't a prob, especially if I'm doing panoramics).
Being a Canon man I'm not familiar with the Nikon nomenclature on mount types and designations
Now I know Novoflex do a high quality one and there's a crowd called
16:9.net who seem to do one. However these both appear to be like rocking horse whatsit so I was wondering if someone a) could explain the Nik set up, and b) point me in the direction of a decent adaptor, and one that's in stock.
The Canon 16-35L II would be an obvious upgrade over my 17-40L but the Nik is wider, (better?)
and a similar price. 
Cheers
Mike