The Canon 16-35mm f/2.8 L USM is a high-performance, wide-angle, L-class zoom lens with USM autofocus. The wide, 16-35mm zoom focal length is great for landscapes, groups of people, big spaces and other large subjects.
Fast Aperture: The large aperture of this lens helps give you fast shutter speeds in available light and excellent depth-of-field control.
USM: Canon USM ultrasonic autofocus is faster and quieter than mechanical autofocus systems.