how do u even consider a wobbly lens well built? 15-85 is a lot better than the wobbly 17-55. the build of the 15-85 is solid, heavy and tight. the pieces are fit together very tightly. the zoom ring turns very smoothly and it stays where it is at 17mm and 85mm. no creep at this range. but between 24-50mm there's creeping. the zoom ring is way smoother and tighter than the 17-55. 17-55 can't even turn properly.