Sigma 17-50mm f/2.8 EX DC OS HSM FLD Large Aperture Standard Zoom Lens for Nikon Digital DSLR Camera Large aperture, stabilized, standard zoom lens FLD glass with performance equal to fluorite Carrying case, lens hood, front & rear caps. Lens Construction : 17 Elements in 13 Groups OS is not available in Pentax and Sony mounts. Maximum Magnifications 1:5, Minimum Focusing Distance 28 cm / 11 in