Sigma 800mm f/5.6 EX DG HSM APO Ultra Telephoto Lens for Nikon SLR Cameras Dedicated to Nikon AF SLR cameras Uses an ultraquiet hyper-sonic motor (HSM) Two extraordinary low dispersion (ELD) glass elements, which help reduce chromatic aberration Optic materials are lead- and arsenic-free ecological glass Rear rotary filter holder for easy use of polarizing filters