Sigma 50mm f/1.4 EX DG HSM Lens for Nikon Digital SLR Cameras 50mm focal length 75mm equivalent focal length on APS-C cameras, 100mm equivalent focal length on Four Thirds / Micro Four Thirds cameras, 80mm equivalent focal length on Canon APS-C cameras F1.4 maximum aperture; F16 minimum Ring-type ultrasonic-type AF motor with full-time manual focusing 77mm filters 0.45m/17.72" minimum focus Available in Canon EF, Four Thirds, Pentax KAF3, Sony Alpha, Sigma SA, Nikon F (FX) mounts