Super wide-angle zoom lens designed exclusively for digital SLR cameras It covers a superwide angle of view 102.4° to 63.8°. Three pieces of Special Low Dispersion (SLD) elements and three aspherical lens elements produce top quality optical performance. Inner focusing system ensures the length of the lens remains unchanged whilst controlling aberrations. Equipped with HSM (Hyper Sonic Motor) system. Minimum focusing distance of 24cm (9.4) at all focal lengths. Relatively compact, lightweight for an ultra wide-angle zoom lens. Sigma Corporation is pleased to announce the launch of the new 10-20mm F4-5.6 EX DC HSM lens. 10-20mm F4-5.6 EX DC HSM lens allows enjoyment of super wide-angle photography and it is a very powerful tool for indoor shooting and landscape photography with APS-C size image sensors of digital SLR cameras. Wide angle of view (102.4 ° at 10mm and 63.8 ° at 20mm) offers the photographer greater freedom of expression. Three SLD glass elements are employed for effective compensation of color aberration, which is a common problem with super-wide angle lenses. One piece of glass mold and two hybrid aspherical lenses, offer excellent correction for distortion, as well as all types of aberration. This lens is equipped with an inner focusing system, and the models which are equipped with HSM system provide quiet, high speed autofocus shooting and also offer full time manual focusing. It has a minimum focusing distance of 24cm (9.4) at all focal lengths. The non-rotating lens barrel perfectly suits the petal shaped lens hood. A circular polarizing filter can also be used conveniently. The appearance, specifications, and the like of the product are subject to change for improvement without notice. Vignetting will occur if the lens is used with digital cameras with image sensors larger than APS-C size or 35mm SLR cameras.