The Sigma 180mm f/2.8 APO Macro EX DG OS HSM Lens is a high-speed macro lens offering a magnification ratio of 1:1 and a focal length of 180mm. This lens is compatible with the Canon EF mount for use on full-frame and APS-C DSLRs.This lens incorporates 3 FLD glass elements for color aberration corrections, as well as a floating inner focusing system to reduce other aberrations such as field curvature and distortion, resulting in accurate scene rendition from 1:1 magnification to infinity. A Super Multi-Layer coating helps to eliminate ghosting and flare as well as produce images with more contrast and sharpness. The rounded 9 blade diaphragm also provides an appealing bokeh, especially when photographing at the maximum aperture or at 1:1 magnification.The integrated OS (Optical Stabilizer) system permits users to photograph handheld with shutter speeds up to 4 stops lower than usually possible. An HSM (Hyper Sonic Motor) is also incorporated into the design, ensuring quiet and quick auto focusing and manual focus capabilities.