Sigma 170-500mm f/5-6.3 DG RF APO Aspherical Ultra Telephoto Zoom Lens for Minolta and Sony SLR Cameras 170-500mm ultra-telephoto zoom lens with f/5-6.3 maximum aperture Multi-layer lens coating reduces flare and ghosting for optimal color balance Aspherical lens and 3 special-low-dispersion (SLD) glass elements Rear focus systems ensure high performance stability and ease of use Measures 3.6 inches in diameter and 9.1 inches long; weighs 47.4 ounces