A compact and lightweight 400mm super telephoto AF lens driven by a ring USM (Ultrasonic Motor). The optical system incorporates one Super UD (Ultra-low Dispersion) glass lens element (2nd) with an optical effect similar to fluorite, and one UD glass element(5th), comprehensively eliminating the secondary spectrum and realizing extremely sharp, high-contrast imaging performance at almost same level as EF400mm f/2.8L USM. Other professional features are: a built-in lens hood with locking mechanism, dual manual focusing rings, a removable ring-type tripod mount, full-time manual focusing, and focus range selector for 3.5m to infinity or 8.5m to infinity. Extenders EF1.4X and EF2X can be used with manual focusing.