Sigma's 70-300mm f/4-5.6 APO DG Macro Lens is one of several tele zoom lenses. By incorporating the autofocusing motor into the lens itself, it can now autofocus with all Nikon DSLR cameras (including the D40, D40x, etc.). In addition, with the motor built into the lens, focusing will be quieter and more responsive.This lens 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 DG lens design corrects for various aberrations. This lens is specially coated to get the best color balance while also cutting down on ghosting caused by reflections from the digital image sensor.Macro photography with a 1:4 maximum close-up magnification at focal lengths from 70mm to 200mm and 1:2 maximum close-up magnification at the 300mm focal lengthSwitch for changeover to macro photography at focal lengths between 200mm and 300mm with a maximum close-up magnification from 1:2.9 to 1:2The built-in autofocusing motor ensures quiet and high-speed auto focusing with full time manual focus override.The lens materials used in this product are lead and arsenic free ecological glass