In visual comparison, the Canon EF 70-200mm is 1: 2.8 L IS II USM but really better to classes! A super sharpness (even with both Canon converters) over the entire zoom range.
After I had a EOS 5D MK II gained me two months later, I was skeptical at first whether the image quality in the corners remains so good ... and I must say that I was not disappointed. Sure, a slight sharpness drop in the corners of the VF can be seen. This is compared with the figure of my old Sigma above near the image center (!) With the same panel but still equivalent, if not a touch better. Unfortunately I kan make any direct comparison more, because the Sigma has been sold.
The IS really delivers the 4 f-stops: On a freehand pictures without flash in the room is at 200mm at f 2.8 and 1 / 10s from 6m distance the fine scale labeling of pots (about 3mm in size) displayed correctly!
The AF is not only very fast, but also very accurate.
The only negative points I can think of the rather high weight and the rather high price. On weight you can in this lens class certainly does not change much - Aperture 2.8 is now time because the lens diameter hard. ... But if you're willing to pay the price difference to its predecessor or other lenses with the same initial panel, everyone must decide for themselves. I for one did not regret it!
Oh yes, I use it mainly for sports and wildlife photography ... or even if you in the normal landscape pictures or in an appropriate focal length needed.
