The 18-200mm f3.5-5.6 OS is equipped with Sigma own unique OS (Optical Stabilizer) technology. This system uses two sensors inside the lens to detect vertical and horizontal movement of the camera by moving an optical image stabilizing lens group, to effectively compensate for camera shake. It also automatically detects panning movement of the camera and compensate for camera shake when shooting moving subjects such as motor sports. A Special Low Dispersion (SLD) lens and three aspherical glass elements provide excellent correction for all types of aberrations and produce a high level of optical performance throughout the entire zoom range. The super multi-layer lens coating reduces flare and ghosting while producing the best color balance.