Sigma 24-70mm F2.8 DG HSM OS Art Featuring a brand new OS and highly efficient and fast AF system, the revamped 24-70mm F2.8 Art embodies all the technical qualities and finesse that define the high-performance Sigma Global Vision Art series. Covering a wide range of shooting scenarios, the 24-70mm workhorse DNA includes three SLD (Special Low Dispersion) glass elements and four aspherical elements to reduce chromatic aberration. The 24-70mm F2.8 Art aspherical elements use Sigma's groundbreaking thicker center glass design and highly precise polishing process, delivering stunning images and bokeh effects. The lens' purpose-built structure boasts a new metal barrel for optimal durability with TSC composite internal moving components designed to resist thermal contraction and expansion