Summary: This is a great lens for the money. They could charge more and it would still be a good buy. It's very sharp edge to edge, and if you use a PS plug-in like Fisheye Hemi (which straightens the verticals), you end up with an ultra wide angle for not much cash. Exposure might be a little weird, depending on your camera. I have a Nikon D200 so aperture priority *mostly* works (sometimes it requires adjusting the exposure + or - just a little). Not a big deal with digital.
Summary: This fit great on my camera body with no problems. No flaws in the lens. The lens is pretty heavy compared to my other lens. It takes a little while to get the hang of it, but once you do you will be very happy you bought it.
Excerpt: Have used for a couple weeks now on my K50. The lens allows you to get some very unique shots and videos.Build quality seems very good. Only concern is how long it will be before I smash something into the front element which does extend out a fair distance, and the need to get objects very close to it.Overall, I'm pleased I purchased it.
Summary: love this lens, it's much slower then I would prefer which is why I only gave it 4 out of 5 stars. But I have used this on multiple photoshoots and some are being published in some magazines. It produces really sharp and interesting photos. But if you have no control of the lighting I recommend having some sort of tripod/monopod to allow a much slower shutter speed.
Excerpt: I really was a bit skeptical about buying a lens that was not NIkkor as that is all I have ever owned, but I wanted to try a fisheye lens and being as I have a full frame camera they were very expensive. I bought this lens and simply set the camera to detect the DX format each time it is attached it and off I was taking pictures. With its Nikon sensor chip I can easily tell when it is in Focus and the images are sharp and clear.
Pros: Easily Interchangeable, Lightweight, Strong Construction