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.