Sigma 500mm f/4 DG OS USM S Canon lens review: Super-sharp shooter

  The lens features the large f/4 maximum aperture desirable for achieving fast shutter speeds; Sigma’s 4-stop image stabilizer (OS) for shake-free images of relatively static subjects, using shutter speeds as slow as 1/30 of a second; and Sigma’s hypersonic autofocus motor (HSM) for responsive AF performance. A focus limiter switch, as well as focus recall controls, help improve focusing performance for photographers shooting in fast-paced environments. Manual focus override is possible in standard AF mode, as well as when using the dedicated MO (Manual Override) mode during continuous autofocus. The Sigma 500mm f/4’s lens design boasts a dust- and splash-proof magnesium