Sigma 50-500mm f/4.5-6.3 APO DG OS HSM SLD Ultra Telephoto Zoom Lens for Canon Digital SLR Camera - International Version (No Warranty) Lens Construction consists of 22 Elements in 6 Groups; 4 SLD (Special Low Dispersion) glass elements provide optimum color correction & sharpness. Offers Sigma's OS System (Optical Stabilization) for handheld photography in low-light situations and HSM (Hyper-Sonic Motor) for quiet & high-speed auto focus. Angle of View: 46.8-5.0, Minimum Aperture: f22, Minimum Focusing Distance: 50-180 cm / 19.7-70.9 in, Filter Size (mm): 95, and Maximum Magnifications: 1:3.1. Supports only Sigma 1.4X MF and 2X MF Teleconverters for use on Canon digital SLR cameras.