"The Sigma 12-24mm F4.5-5.6 II DG HSM is an update to the 12-24mm F4.5-5.6 Ex DG ASP HSM, which has been a photographer favorite since it was first introduced in 2002. Revisions to the lens include the splash-proof design, as well as the inclusion of one Special Low Dispersion (SLD) glass element and four of the company's new ""F"" Low Dispersion FLD glass elements to compensate for color aberration and provide high imagequality. FLD glass is the highest level, low dispersion glass available with extremely high light transmission and performance equal to fluorite glass. The 12-24mm contains three glass mold elements and one hybrid aspherical lens for advanced performance and compact and lightweight construction. It also features Super Multi-Layer Coating to reduce flare and ghosting, and a Hyper Sonic Motor (HSM) to ensure quiet and high-speed autofocus, while allowing full-time manual focus override. Its minimum focusing distance is 11 inches throughout the entire zoom range; its maximum magnification ratio is 1:6.4.|Designed for use with full frame digital cameras. May also be used with smaller APS-c size sensors with a corresponding effective increase in focal length to about 17-35mm with most cameras|A splash-proof design allows for use in harsh conditions.|One SLD and Four FLD glass|Minimum focusing distance of 11 inches"