Tamron AF 10-24mm f/3.5-4.5 SP Di II LD Aspherical (IF) Lens for Pentax Digital SLR Cameras B001P (Model B001P) 10-24mm focal length 15-36mm equivalent focal length on APS-C cameras, 16-38.4mm equivalent focal length on Canon APS-C cameras F3.5-4.5 maximum aperture; F22-29 minimum Micromotor-type AF motor without full-time manual focusing 77mm filters 0.24m/9.45" minimum focus Available in Canon EF, Nikon F (DX), Pentax KAF, Sony Alpha mounts The world's first 2.4X zoom with an equivalent 16-37mm (when converted to full frame) The best magnification ratio in this class of 1:51 Extremely compact and light Flower-shaped Lens Hood and Case Included 77mm Filter size