Excerpt: I bought this lens in hopes of making it an all-in-one lens for most uses when traveling. However, since my Canon T5i has video recording capabilities, my expectation was also to be able to use this lens for video. The autofocus motor on this lens is so noisy that it shows up on the video quite loudly and makes it absolutely useless if you plan on using autofocus for video.
Excerpt: This lens does not focus properly in low light. Lost all my confidence in the lens while shooting a birthday in a medium lit restaurant. I had to switch back to my kit lens canon 18-55 mm to make sure I got the shots I needed as the sigma was all over the place focus wise.It performs much better outdoors. I find the pictures to be soft, THE FOCUS INCONSISTENT, not sharp at all, heavy distortion at 18 mm. I'm returning it.
Excerpt: When I recived this lens. I was exited about it. All the reviews were great. After taking some test shots I noticed that my images where very soft at most of the range when I shot at wide open. Next day I start shooting at f8 to compare Most my photos were sharp. I just could not pass the idea of having soft photos at wide open. Had to return it. I uses Nikon D5100.