A lot of my customers do not believe me when I tell them that the 70-200/4IS is one of Canon's sharpest 70-200's. Probably only beat out by the 70-200/2.8IS-II, for the money, it cannot be beat. I once heard that this lens was "prime" like and didn't believe it until I tried it for myself. If you dont need the 2.8, go for this one. It's very sharp and because it is light-weight, it won't be killing your arms, shoulders and your back all day!