I had long been looking for a wide-angle that can be good to take for travel and easy to handle as well as a certain telephoto range has to not take all my lenses. After many many research on this lens if yes or read nein..viele hours Forums negative and positive statements ... I was always more verunsichert..Nun I took the plunge and got me bestellt..und must sagen..ein Top lens and for my needs (mostly landscapes) ... at Tageslicht..völlig sufficient. From 17-40 mm it depicts diaphragm 8 to the brim sharply. At maximum aperture and 17mm can be if you want to find a certain fuzziness in the edge region, which is simple but weggebügelt by Lightroom. Either I have a very good specimen caught or just a steady hand, because even hand held shots are super. ;-) I tried it on the tripod. The pictures are just top. The technical details I can save at this point, here is already much written. I highly recommend this lens to the current state just recommend and clearly give 5 stars. I will not give it.
Small Update: I have now the 6D and here it makes just as well off. Perhaps a small note: A friend of mine had problems with the lens (blur that is not normal, I've tried it on my camera) and advised him to send in it to a Canon Prof. Service. This he did and now has exactly the imaging performance as mine. So there seems to be a certain series dispersion. Maybe it will help the one or the other has caught such a specimen. And as long as one is still under warranty, the definitely worth it. It brings my opinion nothing the lens at Amazon returned. Because you know if the other is better afterwards? So off it goes to the service, wait a few days and be patient and everything is good ... ;-)