Sigma's 70-300mm f4-5.6 APO DG Macro lens 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.
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.