evan north , Sep 22, 2012; 05:45 p.m.
i have heard mixed reviews regarding both lenses. the nikon was the first tele zoom to incorporate vr and also lacks af-s. this makes it a little slow. also, beyond 300mm its IQ drops a little.
the sigma however, may, or may not, have a better, ( but noisier) optical stabiliser. IQ is known to drop beyond 320mm leaving centre sharpness at 500mm rather poor whatever the aperture..
i have considered both of these lenses and decided to go for the nikon 300mm f4 plus a 1.4 tc. although it has no optical stabiliser image quality is far superior. i would rather this fixed focal length with a good reputation rather than take a chance with either of the other two.