Sigma's 70-300mm f4-5.6 APO DG Macro is one of several tele zoom lenses. It is a compact Apochromatic tele zoom lens incorporating two Special Low Dispersion glass elements in the front lens group plus one Special Low Dispersion glass element in the rear lens group to minimize chromatic aberration. This Tele-Macro Zoom lens is capable of focusing down to 1:2 (half life-size) reproduction ratio at 300mm focal length with superb optical quality. It also has a switch for changeover to macro photography at focal lengths between 200mm and 300mm. The lens materials used in this product are lead and arsenic free ecological glass. The improved DG lens design corrects for various aberrations. This lens is specially coated to get the best color balance whilst cutting down on ghosting caused by reflections from the digital image sensor.