This exciting new zoom lens provides ultra wide-angle coverage to the EOS 20D and Digital Rebel SLR Digital-camera systems. Equivalent to a 16-35mm zoom, it offers excellent performance and optics designed from the ground-up for digital SLR use. Three Aspherical lens elements, plus a Super-UD element, assure image quality. Its ring-type USM means fast and silent AF along with full-time manual focus. It focuses as close as 9.5 inches. Circular aperture design -- natural highlights, even stopped down two stops Electronic diaphragm -- manually-set apertures stay constant from f/4.5 thru f/22 EF-S lens mount -- exclusively for EOS 20D and Digital Rebel bodies Focal length 10 - 22 mm / 35 mm FOV 16 - 35 mm equivalent Construction - 13 elements in 10 groups Diaphragm - 6 blades Maximum aperture F3.5 - F4.5 / Minmum aperture F22 - F27 Closest focus 0.24 m Max magnification 0.17x (at 22 mm) AF actuator USM with full-time manual focus Filter diameter - 77 mm (accepts 77mm optional filters) Unit Dimensions - 83.5 x 89.8 mm (diameter x length) / Weight - 385 g