The Canon EF-S 17-55mm f/2.8 IS USM Lens is a large-aperture lens specifically designed for EF-S type digital SLR cameras, and that offers a super wide angle to short telephoto zoom range, with built-in Image Stabilization. The focal length is equivalent to approx. 27-88mm in 35mm format. This lens features Canon's latest optical Image Stabilizer technology, providing up to 3-stop compensation for image blur caused by camera shake and slow shutter speeds. This ensures clear, crisp images, even in dim light. 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. Note: Only Canon Extension Tube EF 25 II and 12 II fit on this lens. Note! Not suitable for 35mm film SLR cameras or digital camera with image sensor bigger than APS-C size. Only fits on the EOS Digital Rebel series, or 20D, 30D, 40D, 50D, 60D, and 7D SLR cameras. Uses optics designed to take full advantage of the small image circle and short back focus in EF-S lenses Features three aspherical lens elements (two types) as well as a Super-UD glass element for high image quality at all focal lengths Optimized lens coating minimizing flare and ghosting prone occurring with digital cameras Ring-type USM provides ultra-quite, super-fast, precision auto focusing and predictive tracking Inner Focusing and new AF algorithms, with full-time mechanical manual focusing Circular aperture diaphragm produces brilliant out-of-focus characteristics