Sigma 17-70mm f/2.8-4.5 Lens - Zoom Lens, for Digital SLR, Focus: Autofocus, Max Aperture: f/2.8-f/4.5, trans-standard zoom stabilized, designed for APS-C sensor (35 mm equivalent of a 27-112 mm), ideal for the photo of portrait, reportage, macro and low light Lens construction: 17 elements in 13 groups including 3 aspherical lenses and 2 years