Three Aspherical lens elements, plus a Super-UD element, assure image quality. Its ring-type USM means fast and silent AF along with full-time manual focus. It focuses as close as 9.5 inches.  This exciting new zoom lens provides ultra wide-angle coverage to the EOS 20D and Digital Rebel shooter. Equivalent to a 16-35mm zoom, it offers excellent performance and optics designed from the ground-up for digital SLR use.

Features

• Relatively compact size and light weight for an ultra-wide zoom lens
• Excellent optical quality and true wide-angle coverage with select digital SLRs
• Superior AF performance and speed, with full-time manual focus by simply turning ring
• Close-focusing to 9.5 inches -- fill the frame with subjects as small as 3.6 x 5.4 inches
• Inner focusing system (no front element rotation); length doesn't change if zoomed
• Circular aperture design -- natural highlights, even stopped down two stops
• Electronic diaphragm -- manually-set apertures stay constant from f/4.5 thru f/22
• EF-S lens mount -- exclusively for EOS 20D and Digital Rebel bodies

A circular aperture provides a pleasing background blur when shooting with a wide aperture; ideal for creating a sense of depth and getting your subject or model to stand out from the background.  With its effective focal length range of approximately 16-35mm in 35mm format, the EF-S 10-22mm f/3. 5-4. 5 USM is a remarkable lens with outstanding image quality that will take your photography into new dimensions and areas of dramatic expression. The super-wide zoom not only gives you the freedom to get exactly what you want in the shot, it dramatically alters perspective to allow for dynamic expression. The lens allows you to get extremely close to subjects, exaggerating the difference in size between a near object and its background. Creative photographers can use this phenomenon to create excellent separation between subject and background for a strong sense of presence, or for a pan-focus effect with everything from foreground to background sharply in focus. Exceptionally light and compact for its focal length range, the EF-S 10-22mm f/3. 5-4. 5 USM also has an incredibly close minimum focusing distance of just 24cm. A ring-type USM works in concert with the camera to provide super-fast, precision auto focusing and predictive tracking - with full manual override available at any time. Designed specifically for digital photography, the lens has specially shaped lens elements and Super Spectra coatings to suppress ghosting and flare, which can be caused by reflections off digital camera sensors. An exclusive optional lens hood can further reduce the incidence of flare.