Amazon.comDesigned exclusively for Canon digital SLR cameras, the ultra-wide-angle 10-20mm offers a view from 102.4 to 63.8 degrees, making it ideal for landscape photography and other vast applications. The lens is distinguished by its three special low dispersion (SLD) glass elements, which effectively compensate for color aberration, and its aspherical lenses, which provide maximum correction for distortion and various aberrations. As a result, the lens produces an extremely high image quality throughout the entire zoom range. The HSM-equipped models, meanwhile, produce fast autofocus (AF) speeds and quiet shooting while still letting you perform full-time manual focus. Other details include a minimum focusing distance of 9.4 inches at all focal lengths and an integral petal-type hood to block out extraneous light.Lens Elements and CoatingThe new multilayer lens coating and lens design reduce flare and ghost--a common problem with digital cameras--while also creating an optimal color balance throughout the entire zoom range. At the same time, the lens offers three SLD glass elements that effectively compensate for color aberration, along with a piece of glass mold and two hybrid aspherical lenses that offer excellent correction for distortion and all types of aberration.Inner Focusing System and HSMThe lens incorporates an internal focusing system that eliminates front lens rotation, letting you use a petal-type hood to protect from additional glare. And models equipped with a Hyper-Sonic Motor (HSM) produce silent, high-speed autofocus and full-time manual focus for Sigma, Canon, and Nikon D-mount lenses.Best Consumer LensThe Sigma 10-20mm lens is so respected that it was named the best consumer lens in Europe (2006) by the Technical Image Press Association (TIPA), a collection of 31 publications from 12 countries. According to TIPA, the 10-20mm lens offers a versatile range of wide-angle focal lengths, a good optical performance, and a budget price, making it an excellent investment for owners of DSLRs with APS-C format sensors. Its sharpness remains constant throughout the zoom range, and its compact size makes it an ideal companion for shooting travel, landscapes, or architectural subjects.Lens construction: 14 elements in 10 groups Angle of view: 102.4 to 63.8 degrees Number of diaphragm blades: 6 Minimum aperture: f/22 Minimum focusing distance: 9.4 inches Maximum magnification: 1:6.7 Filter size: 77mm Dimensions: 3.3 inches in diameter and 3.2 inches long Weight: 16.4 ouncesFrom the ManufacturerThe 10 to 20 millimeters f4 to 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 degrees at 10 millimeters and 63.8 degrees at 20 millimeters) 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 24 centimeters (9.4 inches) 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. It covers a superwide angle of view 102.4 to 63.8 degrees 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 24 centimeters (9.4 inches) at all focal lengths Relatively compact, lightweight for an ultra wide-angle zoom lensNote to customers: Vignetting will occur if the lens is used with digital cameras with image sensors larger than APS-C size or 35mm SLR cameras.