At first glance, this lens seems too good to be true. It costs around 15% of Canon equivalents, although admittedly it's manual only. However, the truth is that it's a 14mm lens, so it's got tons of depth of field at any aperture and it's not the kind of lens you'd use to isolate individual elements through focus techniques. I used mine to shoot a performance in a small, low-light location and quickly learned to judge the distance to my subjects, which worked well enough. There were a few headlights in the frame, which also didn't cause any annoying lens flare. I did some testing earlier in the day, photographing black text against a sunlit white background. I did notice some color fringing around the edge of the frame, but that's a worst case scenario and to be honest my later shots didn't give it away. I used mine at F4 so had a stop and got good sharpness throughout the frame. I've heard it's a bit soft wide open, but the truth is I try to avoid lenses wide open at all costs as you never get their full sharpness. So all in all a very economical and satisfying package for me. So why four stars? The included soft case was covered in lint and of course the lens has a large glass eye on the front that cannot be covered by a filter that attracts lint that can be visible in your images at narrow apertures. Otherwise the construction of the lens is very good with a solid body and nice smooth focus and aperture action. So if you want to try ultra wide angle photography but don't want to part with a large chunk of your monthly salary, I recommend you buy this lens. Used on a Canon EOS 5D Mk3.