The Sigma 10-20mm f/4-5.6 EX DC HSM is a super wide angle lens. This review will show all important aspects like build quality, zoom and focus ring abilities, a test of the picture quality and a lot of sample footage.
Get the lens here!
http://amzn.to/2mUQh1k (US Amazon)
http://amzn.to/2mwYd6j (German Amazon)