Introduction Specifications and FeaturesAnnounced in the summer of 2015, the Sigma 24-35mm f2 DG HSM Art is a high-speed, constant-aperture, full-frame zoom covering three of the most commonly-used wide-angle focal lengths; 24mm, 28mm and 35mm. With a bright maximum aperture, this single model is designed to compete with the equivalent fixed focal length f1.8/2 and f2.8 lenses from Canon and Nikon. On an APS-C camera, the Canon-mount model has the equivalent focal length of a 38-56mm lens.This wouldn’t be an Art-series lens without a complex optical construction and a judicious mix of exotic glass types. It