This large-aperture zoom lens features the sharpness and image performance of a single focal length lens with a constant, large aperture of f/2.8 throughout the entire zoom range. The optical system includes an ultra-precision ground and polished glass aspherical lens element(1st) that provides a high level of contrast and sharpness at all shooting distances. Fast and silent AF and full-time manual focusing are achieved by a USM (Ultrasonic Motor), inner focusing system and lightweight lens elements. As the filter attachment ring does not rotate during focusing, 77mm PL-C filters can have good operability. The EW-83B petal-shaped lens hood is designed with sufficient length to provide highly-effective shading of unneeded light throughout the zoom range.