Sigma 100-300mm f/4 EX DG IF HSM APO Fast Aperture Telephoto Zoom Lens for Canon SLR Cameras Hyper sonic motor ensures a quiet, high-speed autofocus Inner focusing system allows attachment of petal-shaped hoods and filters Special low dispersion glass for high image quality Focal length: 100 to 300 millimeters Designed for Canon digital SLR cameras