Canon EF 70-200mm f/2.8L IS III USM Lens One of the most versatile lenses available, the EF 70-200mm f/2.8L IS III USM from Canon is an L-series telephoto zoom distinguished by its bright design and advanced optics. Ideal for a variety of subjects ranging from portraiture to sports, the fast constant f/2.8 maximum aperture excels in difficult lighting conditions and also offers increased control over depth of field for isolating subjects. The optical layout makes use of one fluorite element and five UD elements to suppress chromatic aberrations and color fringing in order to realize a high degree of clarity throughout the zoom range. An Air Sphere Coating is also featured, and works to reduce flare and ghosting for greater color fidelity and contrast in all conditions. Complementing the speed and optics is an Optical Image Stabilizer, which compensates for 3.5 stops of camera shake to better enable working handheld and in low-light situations. A ring-type USM and internal focusing mechanism also afford quick, quiet, and accurate autofocus performance, as well as full-time manual focus override. Additionally, this lens is weather-sealed for use in trying environmental conditions. Versatile telephoto zoom is designed for full-frame Canon EF-mount DSLRs, however can also be used with APS-C models where it provides a 112-320mm equivalent focal length range. Bright constant f/2.8 maximum aperture affords consistent performance throughout the zoom range and offers notable control over depth of field for working with selective focus techniques. One fluorite element and five ultra-low dispersion glass elements noticeably reduce color fringing and chromatic aberrations for high clarity and color fidelity. An Air Sphere Coating (ASC) has been applied to lens elements to reduce backlit flaring and ghosting for maintained light transmission and high contrast in strong lighting conditions. An Optical Image Stabilizer helps to minimize the appearance of camera shake by up to 3.5 shutter speed stops to better enable working in low-light conditions and with slower shutter speeds. In addition to the single-shot standard IS mode, a second mode is also available that it optimized for panning. A ring-type Ultrasonic Motor (USM), along with an internal focusing system, is employed to deliver fast, precise, and quiet autofocus performance as well as full-time manual focus override. Focus Limiter switch lets you constrain the focusing to two different ranges to suit different applications: 3.9'-infinity or 8.2'-infinity. Rounded eight-blade diaphragm contributes to a pleasing out of focus quality that benefits the use of shallow depth of field and selective focus techniques. A weather-resistant design protects the lens from dust and moisture to enable its use in inclement conditions. Additionally, fluorine coatings have also been applied to the front and rear lens elements for further protection against fingerprints and smudging.