Great price on these lenses!
I couldn't fin any other place selling these under the 549£ mark.
Ken Rockwell review: http://www.kenrockwell.com/sigma/18-35mm-f18.htm
"ruly a revolutionary product, the Sigma 18-35mm 1.8 DC HSM is the first wide-angle to standard zoom lens to achieve a large aperture of 1.8. Designed specifically for APS-C sized sensors, the Sigma 18-35mm 1.8 translates to 27mm-52.5mm on 35mm camera."