Re: Nikkor AF-S 300mm f/4D IF-ED
Hi Bird201, I think a lot of people are looking for the kind of thorough review that DxOMark do for the Nikon 3000f4, the 300f4 plus TC-14E ii, and the Canon 400f5.6. ::) There is no substitute for these lenses in the keen amateur ("prosumer") bird photography market. It's widely acknowledged that the long tele-zooms are not sharp where needed (at the long end), as DxO's own results show - something people usually find out too late :'( The exceptions are usually too expensive (eg 200-400 f4). Even professionals use the Nikon 300f4 plus TC-14E ii combo and swear by it (eg: http://photographylife.com/reviews/nikon-300mm-f4d)
People often um-and-ah about whether to go Nikon 300f4+TC14 or Canon 400f5.6 (eg see: http://www.fredmiranda.com/forum/topic/1067193/0).
The only review site I have found that allows a comparison of both on the same terms is photozone.de, where the 300f4+TC14 (and 300f4+TC17) results are included along with the 300f4 alone:
It would be a fantastic contribution if DxOMark could so an article comparing the Nikon 300f4, 300f4+TC14 and Canon 400f5.6 and asking what the best options are for amateur birders 8)