It is first time to try Sigma 10-20 @10mm and @13mm for a Sony A57. This lens was on sale yesterday and I bought it right after reviewed some comments. The initial idea was to try a Tokina 11-16mm which said to be a lot more sharp ( for still picture ). Since I am doing more on video shooting so it's better to get a lens with bigger range of zoom. I also had an old telephoto zoom lens with 170-500mm from Sigma and that one dong well so far ( just a little AF nose for video ) . This ex-experience with Sigma made me change to Sigma 10-20mm. This new lens also comes with a 7 years warranty so I don't have to worry about built quality issue. I have other one for video which is Tamron 18-270mm and I am happy with it, well the Sony one DT 55-300m is also good (quiet ) for video but it luck of range for wide angle. My interest is to try to bring some special view that human eyes would normally not able to see. With this ultra wide lens I hope it can help. Thanks.