The Sigma 17-70mm f2.8-4.5 OS HSM is a large aperture optically stabilised standard zoom lens for digital SLR cameras. The lens is ideally suited for a wide variety of subjects and is designed specifically for digital SLR cameras featuring APS-C size image sensors. The super wide-angle capability of this zoom lens (equivalent range of approx. 27-112mm when used with a Canon digital SLR camera) makes it ideal as an everyday large-aperture lens. In addition, the maximum magnification of 1:2.3 also enables close-up photography. DC lenses are exclusively designed for digital SLR cameras. The image circle (rear of lens) is made to match the smaller dimensions used for the image sensor on digital cameras. As a result these lenses are also more compact and lightweight, and are better matched to digital SLR cameras.