Canon EF 70-200mm 1:2.8 L IS II USM review
Studio Tests - APS-C format
The 70-200mm F2.8 L IS II USM puts in a very impressive performance on APS-C format. It's pretty well as good wide open as it is stopped down at all focal lengths, and while it's least strong at the long end, overall there's very little to complain about here at all. Compared to the previous 70-200mm F2.8 L IS USM, there's really no contest - the new version is streets ahead.
Sharpness on APS-C is very impressive, even wide open. Stopping down can sharpen up the corners a little bit, however at the center of the frame the lens is pretty well as sharp wide open as it will ever be. There's strong evidence for a shift in focus on stopping down at 70mm, which is something to look out for when focusing manually. The lens is fractionally less sharp at 200mm compared to shorter focal lengths, but it's still more than acceptable.
Chromatic aberration is exceptionally low. If you look really closely there's a tiny bit of fringing at the extremes of the zoom range, but it's unlikely ever to be a problem in normal use.
We consider falloff to become perceptible when the corner illumination falls to more than 1 stop less than the center. There's simply nothing to be concerned about here at all.
Distortion is extremely low, from 0.5% barrel at 70mm, through neutral at 100mm, to 0.4% pincushion at 200mm. This is absolutely nothing to worry about, as it will be essentially imperceptible in normal use.