One of the most versatile lenses available, the Canon EF 70-200mm f/2.8L IS III USM Lens 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.