Not so long ago a 10-22mm zoom lens with any sort of useable performance would have been impossible, but Canon have managed to make it a practical reality. While the Canon 10-22mm EF-S isn’t absolutely the sharpest lens in my bag - it is very sharp - especially in the center. In fact, for this wide a lens I’m surprised at how sharp it is.  It also feels well made, and, unlike many superwide lenses, resistance to flare is very good, which is very important, as with such an extreme angle of view, flare is often a big problem. Although to an extent distortion is what this sort of lens is about, technical distortion levels are also reasonably low.  Overall, from any  point of view, this is a great lens. If you have a Canon Digital SLR camera, and aren’t planning on going full frame - go out and buy one- you’ll love it!