The Sigma 18-200mm f/3.5-6.3 II DC HSM Lens for Sony offers an "all-in-one" super-zoom lens solution, from wide-angle to long telephoto. It provides the equivalent focal range of approx. 29-320mm when used with a Sony digital camera. The 18-200mm has a Hyper Sonic Motor (HSM) for quiet, high-speed autofocus. The 18-200mm's optical design incorporates aspherical lenses and SLD (Special Low Dispersion) glass, which provides the utmost correction for all types of aberrations. It also enables this extended super-zoom lens to be housed in a compact and lightweight construction. DC lenses are exclusively designed for digital SLR cameras. The image circle is sized to match the smaller dimensions used for the APS-C image sensor. As a result these lenses are also more compact and lightweight, and are better matched to digital SLR