This is the world's first 180 mm macro lens incorporating a magnification ratio of 1:1 and a large maximum aperture of F2.8. It benefits from Sigma's original optical stabilizer function and the wide F2.8 aperture allows faster shutter speeds for narrow depth of field, enabling photographers to emphasize the subject. Three FLD ("F" Low Dispersion) glass elements provide excellent correction for color aberrations. This lens incorporates Sigma's floating inner focusing system. This minimizes aberrations which occur as shooting distances change, and enables stable rendering of the image from infinity to 1:1 magnification. The super multi-layer coating reduces flare and ghosting and provides sharp and high contrast images even at the maximum aperture. Equipped with Sigma's own propriety OS (Optical Stabilizer) system, this lens offers the use of shutter speeds approximately 4 stops slower than would otherwise be possible, enabling handheld close-up photography. The incorporation of HSM (Hyper Sonic Motor) ensures quiet and high speed autofocus as well as full-time manual focus capability. This lens has a rounded 9 blade diaphragm creating an attractive blur to the out of focus areas of the image. At 1:1 magnification, this lens has a focusing distance of 18.5-inch, which is a greater working distance than shorter focal length macro lenses. This is advantageous when taking pictures of highly sensitive subjects such as butterflies and insects.