This is an excellent lens that does exactly what it’s supposed to do. Optically, it’s also excellent. You need to think seriously about whether you know what you’re doing or anything about photography if you buy this for a Canon digital camera that’s less than full frame.
You should probably stick to point and shoots until you understand lens conversion factors. If you don’t understand digital crop factors and can’t read basic specs, you either need to hold your money or find a dealer that you can trust to explain it to you. But the manufacturer shouldn’t be accused of making a bad product because you don’t understand the specs.
A previous user gives a poor rating because he either didn’t read or understand the lens specifications. The rating was retain while most of the review was deleted because it simply didn’t make sense. If you tried to use a 8×10 wide angle lens on a digital slr camera, you’d end up with a super telephoto because you’re only using a portion of the image circle. Someone who calls this lens worthless because he bought first and thought later is blaming Sigma for his lack of attention to the laws of optics and of physics.
When you buy lenses for digital cameras, you have to take your brains out of your boots. This is a fisheye lens that’s excellent on digital cameras, You get the full fisheye effect on a full frame digital camera — OR at full 35 mm. You don’t get the same effect on most DSLRS. When Panasonic Lumix claims 28mm lens width in its new line, it’s not serious, but is referring to the apparent focal length when compared to 35mm film.
The lens can be used on cameras like the 20D or 30D which have a 1.6x crop factor. The news high speed top End EOS 1D Mark III will also have a crop factor of 1.3 while the 1ds and 5D are both full frame and will take full advantage of the 180 degree (on the diagonal) that this lens and other fisheyes offer. This lens is very good close to the optical quality of the Canon fisheye — I’ve used both
