Even relatively long, this lens is in my camera bag and I was always torn between the possibilities offered me the 10mm and the often disappointing results for me (especially in the border area). I had a total of 3 lenses from 10-20mm here. The first lens went back the same as the results in the image were blurred all right. After that I had another two Sigma lenses to choose from and I have chosen the better of them. Nevertheless, it always led a shadowy existence in my camera bag, because I was never really happy with the results and most only have a maximum of photographed with 12mm as the results thus were somewhat better. When I had dug it a few weeks ago again, I was disappointed with the results and I have decided to sell the lens and in the future to take pictures without UWW because my Canon 10-22mm was just too expensive for my usage profile. When I back a little have dealt with the subject UWW, I noticed the positive reports for Canon 10-18mm eye. The price was tempting (239 euros) and corresponded to the second value of Sigma. Therefore, I slammed and yet given the topic UWW a chance. Only so I could see what kind of three "cucumber" from Sigma I had before. That was as different as day and night.
The Sigma is indeed processed valent and is better equipped (hood, lens case), but that does not help me continue in the photos.
Considering the fact, the 10-18mm (with IS) for substantially less money a much sharper image quality is achieved with the Canon, I can only give the Sigma a star (plus a grace Stern because of equipment).