This is probably the best lens I've ever bought ... until now;) the sharpness is simply a Traun and is my Canon EF 100mm f2.8 macro in no way inferior to what is just amazing for a zoom lens. The good piece only has a luminous intensity of 4 is not so tragic, and is very well compensated by the IS, with a little practice at 200mm and an exposure of 1/15 quite sharp images possible. In the F4 is not f2.8, I am aware, I myself have long struggled with me if I would prefer to buy the Big Brother without IS, because almost 2,100 for the 70-200 F2.8L IS II is with me just not inside. Anyway, I did but then decided to go for the 4-and no regrets. At the processing you do not need anything to say that is just great. However, the IS works clearly heard and took me only a little bit insecure, but this should be normal. So to me, there is the full purchase recommendation and saved for all those who like me can not endscheiden between 2.8 without IS, 2.8 with IS, or at least save some and f4 with IS ... it is by no means at the wrong end and it's worth every penny.
