This is one of the finest telephoto zoom lenses in the EF line, it is 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. In addition it's compatible with Extender EF 1.4x II and 2x II.
The Canon EF 70-200mm f/ 2.8L USM lens is a wide-aperture telephoto zoom designed for professional photographers and advanced hobbyists. It's one of the most popular telephoto zoom lenses in the world. Designed to work with both full-frame and APS sensor Canon DSLRs, this fast autofocus high-performance lens includes four UD glass elements, which promote contrasty, accurate images. The wide constant f/ 2.8 maximum aperture provides shallow depth of field so the subject is better separated from the background. A focus range limiter helps reduce focus time. Its ultrasonic motor focuses quickly and smoothly.
Minimum focus is 4.9 feet. A removable tripod collar is included. What you should know about this lens: Compatible
with tele extenders: You can increase this lens's range--The lens is compatible with the Canon Extenders EF 1.4 x and 2x II.
Stellar image quality: Image quality is comparable to that usually achieved with a prime lens thanks to four UD glass elements that correct chromatic aberrations.
Wide aperture: The constant f/ 2.8 maximum aperture makes the camera suitable for low-light use.