When I bought my first Canon camera, the first lens I got was the Canon 17-85 IS. I have used it for more than one year on the old 350D; I liked its fast autofocus, its versatility and the image quality was quite good, even though it has a pretty noticeable chromatic aberration and distortion. In 2009, Canon has announced the 17-85 replacement: the new 15-85 is a bit wider and it promises better image quality. Does it maintain the promise? I have tested it on my Canon 7D, together with the Sigma 18-125 OS, a lens that offers similar features at a much lower price.