Sigma 18-50mm F/2.8 EX DC Lens for Minolta and Sony Digital SLR Cameras EX lens series denotes excellence of engineering and new technology. Large aperture of f/2.8 throughout the entire zoom range. Correction for various types of aberration provided by one SLD (Special Low Dispersion) glass element and two aspherical lenses. Super Multi Layer (SML) coating reduces flare and ghosting from which digital cameras tend to suffer.