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 & Ultra Low Dispersion help to significantly improve image distortion & reduce chromatic aberration. While Advanced Air Sphere & Sub Wavelength coating work to combat ghosting & flare, so you can shoot with complete confidence in environments with unflattering lighting. Fast constant aperture A large, f/2.8 aperture means that you can 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 & 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 & 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 means that you can create beautifully soft background focus. Lens coatings Subwavelength & Air Sphere coating, help to prevent ghosting & flare from effecting your images.