This telephoto zoom lens is designed with Canon s Optical Image Stabilizer technology while retaining compactness and lightness in response to the demands of photographers. This high zoom ratio lens is equivalent to a focal length of 88-400mm in the 35mm format (when used on Canon EOS cameras compatible with EF-S lenses) and the image stabilizer effect is equivalent to a shutter speed about 4 stops faster than the same size lens without Image Stabilizer. In other words if the slowest shutter speed you could formerly hold a 250mm lens steadily was 1/250th of a second with Canon s 4-stop stabilization correction you could hand-hold at shutter speeds as slow as 1/15th of a second. It also uses a UD-glass lens element to correct chromatic aberration for excellent image quality throughout the zoom range. This new EF-S telephoto lens with great features delivers excellent.