Sigma 10-20mm f/4-5.6 EX DC HSM Lens for Sigma Digital SLR Cameras 10-20mm focal length 15-30mm equivalent focal length on APS-C cameras, 20-40mm equivalent focal length on Four Thirds / Micro Four Thirds cameras, 16-32mm equivalent focal length on Canon APS-C cameras F4-5.6 maximum aperture; F22-32 minimum Ring-type ultrasonic-type AF motor with full-time manual focusing 77mm filters 0.24m/9.45" minimum focus Available in Canon EF, Four Thirds, Pentax KAF, Sony Alpha, Sigma SA, Nikon F (DX) mounts Super wide-angle lens designed for Sigma digital SLR cameras Hyper Sonic motor 10 to 20 mm focal length 14 elements in 10 groups 3 special low dispersion and 3 aspherical lens elements