Phill if i had'nt spent my money on all this ~Glass for Nikon i probably would have changed over,but as i have to much sigma glass which does'nt hold it's resell value it would cost me a fortune which you and i know is not possible at the present time,and i also like the Nikon design and ease of use(because you know i'm a simpleton realy),and i would be on the phone every weekend asking you if i could borrow the 400mm lol