The optical system consists of a marine bayonet mounted lens system; 0.55X rectilinear, fully coated amphibious conversion lens, vacuum sealed for maximum anti-fog protection; includes square lens hood complete with 3” by 4” (76mm X 101mm) filter slot; sharp focus to ½ inch (1.3mm) of lens, full telephoto zoom capable of 74º wide angle coverage topside and 64º coverage underwater.