Sigma 24-70mm F2.8 EX DG MACRO (Canon) Black

24-70mm F2.8 EX DG MACRO (Canon) To achieve an F2.8 aperture at all focal lengths, it employs three aspherical Lens to provide optimum aberration compensation. Two Special Low Dispersion (SLD) glass elements are provided for color aberration compensation, to assure high image quality.
This lens incorporates a Dual Focus (DF) system that is designed to make the lens easy to hold during autofocusing, and yet provides a large focus ring for easy manual focusing.