I have this lens now say more than a year and can convinced TOP For my EOS 500D it was quite big, but the photos are. In the first few days I had the impression that the lens had a front focus. After several tests and a few days but then the nightmare was suddenly gone and the focus was sitting (I have no explanation for it). Distortion and chromatic aberration are low because Canon can in this price range only marvel (eg 17-85 IS USM). The mechanism is of such high quality as any of my other (Canon) lenses. Once I fell to the lens and it had to be repaired. I sent it to Tamron office in Cologne and had it repaired after one week back. So also the service is right. After more than a year I've been using it with the EOS 7D and am still enthusiastic.
