I recently had a chance to test out the Canon 17-55 f2.8 IS lens. I notice that when shooting in vertical position, the IS doesn't seem to work well, that is, the photo turn out to be soft. All the landscape shots are very sharp, without even paying attention on holding the camera still.
For both photos, the focus is in the middle of the green door:
portrait mode:
http://i.pbase.com …252.khC9iHdl.IMG_5296.JPG![]()
lanscape mode:
http://i.pbase.com …237.bipXHVyo.IMG_5295.JPG![]()

