Sigma 24-35mm f/2 DG HSM Art Lens for Nikon F Short Description F Mount Lens/FX Format Aperture Range: f/2 to 16 FLD & Special Low Dispersion Elements Two Aspherical Elements Super Multi-Layer Coating Hyper Sonic AF Motor Internal Focus; Manual Focus Override Rounded 9-Blade Diaphragm Thermally Stable Composite Material Compatible with Sigma USB Dock