Developed a fault when just over 1 year old. Sent to Canon for repair, great job done, but cost me another £136, which ironically took it up to the price I would have paid originally to Canon. No guarantee the same fault would not have occurred, but I do worry now about buying from third parties.

I have had two copies of this lens now and both have been quite soft at the frame edges and in the corners on a full-frame body, throughout the focal range and even at narrower apertures. I bought this lens based on the numerous glowing reviews, however I just don't see the quality others are apparently seeing. It performs better on a FOVCF body, such as the 50D, but that's not encouraging since the lens was designed specifically for full-frame cameras. Perhaps I have been unlucky and had two bad copies, but my confidence in this lens is such that I shan't be trying a third. One big positive is that it handles chromatic aberration extremely well - in fact, for an ultra-wide, it really is quite impressive!