Sigma 10-20mm f/4-5.6 EX DC HSM wide angle dslr lens

Sigma makes this lens in several mounts, including Sony Alpha/Maxxum, Nikon, Canon, and Sigma. The lens is essentially identical in all mounts.I originally got the Sigma 10-20mm f/4-5.6 EX DC HSM for my Maxxum 7D because I needed a good wide-angle lens for landscape and indoor photography. Because the Maxxum 7D has a sensor that is smaller than 35mm film, this acts as a built in zoom factor of 150%. What this means is all 35mm lenses are essentially zoomed 1.5 times closer than they are when used on a 35mm film camera body. This is great for telephoto lenses, because you get even more zoomed out of them. Your standard 210mm lens functions as a 315mm lens, and at the same aperture. On the wide-angle of things this is problematic. A 24 mm lens, normally an excellent wide-angle, is functionally a 36mm lens. Even an unusually wide 14 mm lens begees a 21 mm. So the Sigma 10-20mm zoom functions effectively as a 15-30 mm zoom lens. Yet that is wide enough.More than most lens manufacturers, Sigma suffers from uneven quality control (maybe less so now than 20 years ago but still to some degree). What this means is that individual samples of Sigma lenses can vary widely in their quality. A good one is very, very good. A bad one can be quite poor. And they can be brand-new in the box sitting next to each other on the shelf. The only way to really know is to test them. There have been numerous reports of individual examples of the Sigma 10-20mm which focus sharply only on one half of the lens, the other half being always slightly blurry (these are reported more by owners of the Nikon and Canon mount versions, but then most of these lenses are probably sold in Canon and Nikon mounts, so by virtue of their being more of them they'll also be more reports of defective ones). I was fortunate in that the lens I purchased did not have any problems. Wide-open there is a lot of softness at the edges, but stopped down a bit its sharp all the way across. There are minor issues of vignetting towards the edges on high contrast subjects, but you only notice this zoomed to 100% in Photoshop. In all this is a great lens for the price, and really allows for wide-angle photography with DSLR cameras.Here are a few images. Camera us the Maxxum 7D firmware 1.10. Sorry they are so small; that's okay for you.Optimal sharpness:10mm @ f/8, 1/300th (Grand Teton National Park)