[. . . ] FOCUSING/ZOOMING Bt • B 2 • B 3 First, loosen the locking screw ® on the focusing/zooming ring ® . To focus, turn the ring until the image on the focusing screen appears sharp and crisp. [. . . ] To find the depth of field at a particular focal length and aperture, first compose and focus the lens on the subject. Then check the numbers on the distance scale opposite the colored lines to find the depth of field at that aperture. The colors of the pairs of lines correspond to different lens apertures. The continuous curved lines of the depth-of-field scale give the reading at any focal length. You can also observe the depth-of-field through the viewfinder by pressing the depth-of-field preview button on the camera. INFRARED PHOTOGRAPHY In infrared photography, the plane of sharpest focus is slightly more distant than the one produced by visible light. As a rule of thumb, you can compensate for shift in focus by referring to the curved red infrared line © engraved between the depth-offield index lines on the lens barrel. After sharply focusing the subject through the viewfinder, check the focused distance and turn the focusing ring to the left until the prefocused distance figure is aligned with the infrared compensation line. NOTES ON USE OF TRIPOD MOUNTING COLLAR With this lens mounted on a tripod via its tripod mounting collar, you may experience some problems when shifting from horizontal- to vertical-format shooting or vice versa in the following situations. In this case, do not force to turn the lens; otherwise, you may damage the equipment. In motor-drive shooting with a remote cord attached to the motor drive's remote terminal or a cord attached to the external power terminal. 5 ft) to infinity (°°) Focusing/zooming control: Via a single control ring; reference marks for focal length settings of 80mm, 90mm, 105mm, 135mm and 200mm are provided Aperture scale: f/2. 8 ~ f/32 on both standard and aperture-direct-readout scales Diaphragm: Fully automatic Exposure measurement: Via full-aperture method; meter coupling ridge provided for AI cameras and meter coupling shoe for non-AI cameras Tripod mounting: Built-in tripod mounting collar rotatable through 360° Attachment size: 95mm (P = 1mm) Filters: 95mm screw-in Mount: Nikon bayonet mount Dimensions: Approx. 99mm0 x 223mm extension from flange; 231mm long (total) Weight: Approx. [. . . ] If this happens, wipe it again with a cotton cloth moistened with alcohol. €¢ To protect the lens surface from dirt or damage, the use of an L37C filter is recommended at all times. [. . . ]