Manufacturer description: 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.