The Tokina atx-i 11-16mm F2.8 CF (CF means cropped frame) is designed as an ultra wide angle zoom lens for APS-C sensor DLSR cameras. It is the only f/2.8 fast ultra wide angle zoom lens for APS-C sized DSLR cameras in the current market (September, 2019). The useful 11-16mm focal length is chosen in order to position this lens as an easy demanded gear after standard zoom lenses or initial wide angle zoom lens to start with. A constant maximum aperture of f/2.8 throughout the entire zoom range is realized to achieve great results in low light environments, for depth of field control and easy manual shooting, while maintaining a reasonable size and weight of the lens. To achieve an exceptional optical performance demanded for ultra wide angle zoom lens in still and video shooting purposes, two aspherical glass elements and two Super-Low Dispersion glass elements were used in order to minimize distortion, manage spherical aberration and astigmatism while achieving excellent edge-to edge resolution and contrast of the entire image. Great efforts were done to control light fall-off at all focal lengths. Anti-reflective multi-layer coating improves light transmission and minimizes reflections while water-repellent coating makes wiping and cleaning the surface of the front glass element easier. True to traditions, Tokina incorporated a lot of metal parts inside the lens for a reassuring built quality and long time utilization in different shooting conditions. The sophisticated exterior design is specifically developed to match the design of contemporary DSLR cameras. Precise attention was also payed to zoom and focus ring rotation which has convenient amount with no play and made just enough tightly damped. The Tokina atx-i 11-16mm F2.8 CF for Nikon F mount incorporates internal silent focusing motor in combination with precise GMR sensor to allow the lens to AF on Nikon bodies that do not have an AF drive gear and motor. Highly valued One-touch focus Clutch mechanism allows to switch between autofocus and manual focus easy The overall length of the Tokina atx-i 11-16mm F2.8 CF does not change when focusing and zooming thanks to internal type of the focus construction. Focal Length : 11-16mm Maximum Aperture : f/2.8 Minimum Aperture : f/22 Automatic Aperture : Yes Angle of View : 104°-82° Minimum Focusing Distance : 0.3m Macro Ratio : 1 : 11.6 Focusing Mode : Automatic Manual Focusing Ring : Yes Autofocus Switch : Clutch Ring Focusing Type : Internal Focus Filter Size : 77mm Coating : Multi-coating Construction E/G : 13 Elements in 11 Groups Aperture Blades : 9 Lens Hood : BH-77B Electrical Contacts : Yes Dimensions : 84x89 mm (Nikon F) - 84x92 mm (Canon EF) Weight 555g