The only con I can think of for the 17-55mm f/2.8 IS is that it tends to hunt for focus in dim light. Other camera/lens combinations have worked better than the 50D and 7D paired with a 17-55 under similar conditions. That said, it's still the best general purpose lens for a crop body. If I could only have one lens, that would be it.


Samara on the Bench by budrowilson, on Flickr