Hi. I plan to upgrade to 5D II possibly soon and I will need to get a full frame wide-angle zoom as well, Canon 17-40 seems like a natural choice. Although its blurry corners at 17mm put me off a bit. Tell me, please, if you are happy with its "corner performance" at 17mm when stopped down to f/11 or do you need to stop it down even further? I can see the exif for the above photo of course, but at this size you can't really tell anything. Thanks