I bought this lens used during the summer for 685 pounds. I just sold it along with all my other Canon gear as ive switched to Pentax but the person who bought this informed me that it has a faulty M/AF focus clutch problem which occurs in the vertical position. Ive used it for landscape with no probs but obviously it's going to have its limits for use until fixed. i didnt notice myself (not an experienced photographer) and ive no idea how much this would cost to repair but need to sell it on ASAP to fund lens purchases for new Pentax k5.