This Sigma 11.1x high zoom ratio lens is designed exclusively for Canon digital SLR cameras and incorporates Sigma's original OS (Optical Stabiliser) function. The Sigma 18-200mm lens is equipped with Sigma's own OS function which uses two sensors inside the lens to detect vertical and horizontal movement of the camera, and works by moving an optical image stabilising lens group to effectively compensate for camera shake. It also automatically detects movement of the camera and compensates for camera shake when shooting moving subjects.