Its interesting to compare the lens at 400mm on the 7D MK II wide open at f/5.6 versus wide open on a 1Ds MK III with 1.4X TC. Note, the lens is better wide open than stopped down, and matches the FF in the corner, but not quite in the center when wide open.
The images are very carefully set up and manually focused to be the best the camera can do. The 7D MK II is a hair better than the 60D, since it has a few more MP, the improvement is proportional.
I wish he had included the 1D MK IV in those tests.
7D MK II at 400mm f/5.6 (center)
7D MK II at 400mm f/5.6 (corner)
1DS MK III with 1.4X TC wide open - f/8 (center)
1DS MK III with 1.4X TC wide open - f/8 (corner)
The images are very carefully set up and manually focused to be the best the camera can do. The 7D MK II is a hair better than the 60D, since it has a few more MP, the improvement is proportional.
I wish he had included the 1D MK IV in those tests.
7D MK II at 400mm f/5.6 (center)
7D MK II at 400mm f/5.6 (corner)
1DS MK III with 1.4X TC wide open - f/8 (center)
1DS MK III with 1.4X TC wide open - f/8 (corner)