[. . . ] After reading this Operating Instructions, keep it for future reference. [. . . ] In case you are unable to focus either at the shortest or longest focal lengths, adjust the back focus of the camera by the following method, referring to the Operating Instructions of the camera. Cover front of the lens with a ND filter according to the prevailing lighting conditions. ) Set the focus ring at [FAR] position, and then adjust back focus of the camera. When grease or fingerprints are on the lens, wipe them off with a lens cleaning paper and lens cleaner gently forming a swirl from the center to the circumference. â· Keep the lens away from dust, poisonous gas, moisture and salt. Object distance Driving coil Damping coil Driving voltage Temperature range Model number Focal length Iris range Min. [. . . ] Object distance Driving coil Damping coil Driving voltage Temperature range Model number Focal length Iris range Min. [. . . ]