Based on widely popular AT-X 11-20 F2.8 PRO DX model atx-i 11-20mm F2.8 CF was redesigned and optimized for contemporary APS-C sensor DSLR cameras in terms of improved specifications andrenovated design with still photographers and video content creators' demands in mind. Focal length 11-20mm that covers equivalent angle of wide prime 18mm, 21mm, 24mm, 28mm lenses makes this lens attractive to be chosen after standard zoom lens or initially possessed wide angle zoom kit lens. A constant maximum aperture of f/2.8 throughout the entire zoom range is realized to achieve great results in low light conditions, for depth of field control and easy manual shooting, while maintaining a reasonable size and weight. To achieve an exceptional optical performance required for ultra wide angle zoom lens 3 aspherical glass elements and 3 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 high contrast through the entire image. Anti-reflective multi-layer coating improves light transmission and minimizes reflections while newly applied water-repellent coating makes wiping and cleaning the surface of the front glass element easier. Minimum Aperture f/22 Maximum Aperture f/2.8 Format APS-C Coating Multi-coated Lens Configuration 12 groups, 14 elements Angle of View 104° ~ 72° Minimum Focus Distance 0.28m Macro Ratio 1 : 8.62 Focus Method Internal Focus Diaphragm blades 9 Filter size 82mm Overall length Canon EF mount: 94.3mm Maximum diameter 89mm Weight Canon EF mount: 570g Hood BH-821