Prized for event, portraiture, & sports shooting, the Canon EF-mount Sigma 70-200mm f/2.8 DG OS HSM Sports Lens is a flexible telephoto zoom characterized by its bright & sophisticated design. The fast constant f/2.8 maximum aperture excels in difficult lighting conditions & also offers increased control over depth of field for isolating subjects. In regard to the optical layout, an impressive 10 low dispersion elements are used to greatly reduce chromatic aberrations & color fringing for enhanced clarity & color accuracy. A Super Multi-Layer Coating is also featured, & helps to suppress ghosting & flare when working in strong lighting conditions. Complementing the optics is an Intelligent OS system, which minimizes the appearance of camera shake for sharper results when shooting handheld. A Hyper Sonic Motor is also used to provide quick & quiet autofocus performance along with full-time manual focus override. The physical design of the lens also incorporates several seals to guard against dust & moisture, & a water- & oil-repellent coating has been applied to the exposed elements to prevent moisture, fingerprints, or smudges from sticking to the surface. in addition, a fixed rotating tripod collar is featured, & has a removable Arca-type compatible foot for wide compatibility with a different tripod or monopod heads