I think you'd get more versatility out of the 17-55mm f/2.8. Wide angle lenses like the 17-40mm generally have a very wide depth of field inherent in their design so you might not get the nice diffused background blur as you would with the 17-55mm. You can always stop the 17-55mm down to increase your depth of field.


Someone correct me if the above statement's not entirely true, I don't want to be giving out bad advice here. It's what I found with the 10-22mm anyway.


Cheers, Sven