Canon EF500mm f/4L IS II USM and EF600mm f/4L IS II USM review – Giants in the rangeBy David Newton - Monday May 27 2013 Lens Review
Looking at the results of telephoto prime lenses tested on the EOS 5D Mark III, both the EF500mm II and EF600mm II are within the top 6 best overall score and image sharpness. Putting these two lenses beside the EF400mm f/2.8L IS II USM lens that has also been through the labs, shows just what Canon have achieved with their Mark II super-telephoto lenses – they are as close to perfection as you can expect to get. Interestingly, the performance differences between the lenses are almost negligible and the only reason the EF400mm f/2.8L IS II USM comes out on top is down to the fast maximum aperture and hence better transmission score.
Of course you would not usually be selecting between these lenses as their focal lengths have very different uses, however, as a comparison of what the best telephoto lenses can currently do, they make an exciting trio, any of which would be a worthy addition to your kit.