The Canon EF 70-200mm f/2.8L IS USM Telephoto Zoom Lens is one of the finest telephoto zoom lenses in the EF line, comparable to a single focal length lens. It has four UD-glass elements to correct chromatic aberrations. Its constant f/2.8 maximum aperture and superb image quality make it one of the most popular professional SLR lenses in the world. Compatible with Extender EF 1.4x II and 2x II. Features: EF mount; telephoto zoom lens Ultra-low Dispersion glass; inner focusing; full-time manual focus 70-200mm focal length f2.8 constant maximum apertureUltraSonic Motor (USM)