When used on digital SLR cameras the AT-X M35 PRO DX lens gives the same angle of view as a 52mm lens. The close focusing distance of the M35 is an amazingly close 5.5 in. (14cm) yielding a macro ratio of 1:1 or life-sized reproduction with excellent sharpness. Its compact size makes it easy to carry almost everywhere and the wide f/2.8 aperture allows for easier viewing in low light situations. The front element of the AT-X M35 PRO DX has a newly formulated WR or Water Repellent optical coating on the glass. This new coating makes marks such as spots left by water or finger-prints much easier to clean than standard multi-coating. Tokina"s exclusive One-touch Focus Clutch Mechanism allows the photographer to switch between AF and MF simply by snapping the focus ring forward for AF and back toward the camera to focus manually. There is no need to change the AF-MF switch on Nikon cameras and there is no second AF/MF switch on the lens for Canon, everything is accomplished by the focus ring. Please Note: * The lens is designed for Digital cameras with APS-C sized CMOS and CCD sensors, not designed for cameras with Full Frame sensors. ** Please note, the Tokina AT-X M35 PRO DX lens itself is not waterproof or water resistant. *** Will not AF when used on Nikon D40 SLR camera body.