To meet user demands for a fast EF-S zoom lens, Canon has specially designed a new lens with a large aperture of f/2.8 for select Canon Digital SLR cameras.The large circular aperture produces a shallow depth-of-field, creating background blur that draws attention to the photographic subject. The lens construction includes UD and aspherical elements, which deliver impressive image quality throughout the entire zoom range. Image Stabilizer lens groups shift to compensate for camera movement so that the image appears steady on the image plane, ensuring clear, crisp images, even in dim light. With a Ring-type USM, inner focusing and new AF algorithms, this lens achieves autofocus quickly and quietly, and with full-time mechanical manual focusing, manually adjusting the focus is possible even in AF mode. Note: Only Canon Extension Tube EF 25 II and 12 II fit on this lens. Not suitable for 35mm film SLR cameras or digital camera with image sensor bigger than APS-C size Features: Standard zoom lens for digital SLR cameras - 17 to 55mm focal range, fast f/2.8 aperture High magnification standard zoom lens specifically for digital SLR's that accept EF-S lenses Image Stabilizer gives the equivalent effect of a shutter speed three stops faster UD and aspherical elements to reduce aberrations for outstanding image quality Inner focus design with ring-type Ultrasonic Motor (USM) for fast and virtually silent operation Circular aperture producing attractive background defocus 35cm minimum focus distance at all zoom focal lengths Manual focussing enabled even during AF mode (full time mechanical focusing) Only environmentally friendly lead-free glass used in lens construction Compatible with: EOS Digital Rebel / EOS 300D Digital / EOS Kiss Digital EOS Digital Rebel XT / EOS 350D Digital / EOS Kiss Digital N EOS 20D EOS 20Da EOS 30D