Just posted: Our hands-on preview of the Sigma 18-35mm F1.8 DC HSM Art lens. The announcement of the world's first constant F1.8 zoom caused a lot of discussion, much of it centered around the idea that the brighter aperture would help APS-C DSLRs to compete toe-to-toe with full frame cameras in many respects. We've had a chance to handle the lens and prepare a preview putting its capabilities in more context. Click here to find out more.