The Sigma 18-200mm f/3.5-6.3 DC lens is specially optimized for digital SLR cameras, and offers an "all-in-one" super-zoom lens solution. This lens provides the equivalent focal range of approx. 29-320mm when used with a Canon digital SLR camera(*).
It's design incorporates aspherical lenses and SLD (Special Low Dispersion) glass that provides the utmost correction for all types of aberrations and 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 (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.