The EF 16-35mm f/2.8L III USM is a premium quality ultra-wide angle zoom lens, with a constant f/2.8 maximum aperture, for the highest image quality possible even in low light conditions. Versatile collection of wide-angle focal lengths EF 16-35mm f/2.8L III USM features a 16-35mm zoom that incorporates a range of wide-angle focal lengths. Premium image quality Large-diameter double-surface Glass Moulded (GMo) lenses and Ultra Low Dispersion help to significantly improve image distortion and reduce chromatic aberration. While Advanced Air Sphere and SubWavelength coating work to combat ghosting and flare, so you can shoot with confidence in environments with unflattering lighting. Fast constant aperture A large, f/2.8 aperture allows you to make the most of available light, while a 9 bladed circular aperture diaphragm helps to deliver stunning depth of field. Durable L-series construction The robust, durable, weather sealed construction of EF 16-35mm f/2.8L III USM helps it to withstand the rigours of professional use. Advanced autofocus EF 16-35mm f/2.8L III USM features a ring-type USM motor and high-performance CPU, which work to ensure faster focusing. Optical System Newly designed optics delivers stunning sharpness right across the frame. A re-designed 5 group zoom mechanism that improves vibration and shock resistant levels. 9 bladed aperture In comparison to the EF 16-35mm f/2.8L II USM 7 bladed circular aperture, the EF 16-35mm f/2.8L III USM contains 9 bladed circular aperture diaphragm, that allows you to create beautifully soft background focus. Lens coatings Subwavelength and Air Sphere coating, help to prevent ghosting and flare from effecting your images.