Quote Originally Posted by Daniel Browning
100-400 at 400mm f/5.6 is not quite as sharp as the 300mm f/4+1.4x, but it's close.




Forgive me for being nit picky, but it looks to me that the 100-400mm is a bit sharper in the center but the 300mm+1.4 is better in the corners. I guess it doesn't make any differance in real world anyway.