Summary: Would prefer full time manual focus, in auto focus mode the focus band is stiff and should not be rotated. I might super glue the lens cap together to make one unit, its a barrel with a normal cap on it but both must be removed. The image quality is amazing, very sharp all the way to the corners. Very short focus distance and massive light gathering allow for macro shots with natural light. A very fun lens.
Excerpt: Fisheye lens are, in my opinion, meant for creative pursuits. At least that's what I use mine for. This is a very good lens. I have a couple of Sigma lens and they haven't let me down yet. Add this to that list.
Pros: Consistent Output, Durable, Easily Interchangeable, Fast / accurate auto-focus, Rugged, Strong Construction
A great lens under good conditions, but don't expect perfection
S. Gonchar, Amazon
9 January 2013
Summary: Hello, Got this just to try out fisheye lenses. During daylight quality is awesome very sharp. Focus is slow (and loud) compare to USM. Focuses all the way down to a few inches so you can get some insane perspectives. During the night, even with AF lamp assist and flash metering thing it focuses about *half* the time ... on 5Dm3, didn't expect that at all. Granted once you lock in focus it's an amazing perspective, 2.8 really helps with low light ...
Summary: It performs great on my Sony A850. This lens is made for a fullframe lens (or a film DSLR), so do not use it on an APS-C camera like the Sony A37 or a Canon EOS 650D or whatever APS-C model, because the crop factor (because of the smaller sensor) would turn this into the equivalent of a 23mm lens roughly.
Excerpt: If you havent used a fish eye before get used to the field of view! I do have pics with my feet in them, lol. I went with the Sigma over the canon to save cash. good choice in that I use this lens occasionally. it performs well for the money if you dont have L glass money.
Pros: Consistent Output, Fast / accurate auto-focus, Rugged
Excerpt: After using the 10mm Sigma Fisheye on my 7D, I needed a lens that would be compatible with my full frame 5D. The 15mm Canon has known issues, those of which the Sigma lack. <br /><br />Although it's a little loud when autofocusing, it's fast and sharp. Even wide open, aberrations are barely present, when compared to the now defunct Canon 15mm.<br /><br />Worth the money and great for video.