• 10-20mm ultra-wide angle lens designed exclusively for Canon digital SLR cameras
• 3 special low dispersion (SLD) glass elements to compensate for color aberration
• Hyper-Sonic Motor (HSM) produces silent, high-speed autofocus; full-time manual focus
• Multilayer lens coating reduces flare and ghost; 9.4-inch close focusing distance
• Measures 3.3 inches in diameter and 3.2 inches long; weighs 16.4 ounces

Product Description
This ultra-wide zoom lens has a wide angle of view from 102.4 – 63.8 degrees and it is exclusive to digital SLR cameras. SLD glass elements effectively compensate color aberration. Aspherical lenses provide maximum correction for distortion and various aberrations; high image quality is displayed throughout the entire zoom range. The HSM equipped models makes fast AF speeds and quiet shooting a reality, and it is also capable of full-time manual focus. It has a minimum focusing distance of 9.4″ (24cm) at all focal lengths. It is also equipped with an integral petal-type hood to block out extraneous light.Amazon.com Product Description
Designed 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 Coating
The 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 HSM
The 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 Lens
The 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 ounces

Sigma 10-20mm f/4-5.6 EX DC HSM Lens for Canon Digital SLR Cameras