Sigma (258955) 105mm f/2.8 EX DG Macro OS HSM Lens for Nikon DSLRs (AF-D) The Sigma 105mm f/2.8 Macro lens is a large aperture macro lens giving full 1:1 magnification also with a rounded 9-blade diaphragm for added smoothness to defocused areas of the image. It is equipped with Sigmas Optical Stabiliser (OS) which corrects for up to 4 stops of camera shake allowing for hand-holding in most instances. Optically the lens uses SLD (Special Low Dispersion) glass to correct chromatic aberration spherical aberration and field curvature giving superb sharpness extra low colour aberration and very low distortion levels. The 142mm close focus gives true macro reproduction but at a longer working distance so there are no camera or lens (or photographer) shadows over the subject and less chance of disturbing living subjects such as insects. There is also a shallower depth of field for the same macro subject when compared to Sigma macro lenses of shorter focal length such as their 50mm or 70mm versions. Equipped with a Hyper Sonic Motor (HSM) focusing with the 105mm is fast and accurate with the ability to override with manual focus. Is also has a Floating Inner Focus system which maintains image quality at all focus points as well as meaning the length of the lens does not change during focusing. Flare and ghosting are drastically reduced by the inclusion of Super Multi Layer Coatings and there is the option of an even greater working distance when paired with an optional Sigma APO Teleconverter. Hood Adapter included for use with APS-C cameras for most efficient reduction of flare.