The Micro-Nikkor 200mm f/4 IF AI was the world's first 200mm 'micro' lens. The internal focusing technology enables the lens elements to move inside the lens and prevents movement of the lens barrel as the lens is focused closer. At its closet focusing distance of 2.34ft the lens produces a 1:2 reproduction ratio. The lens employs Nikon Integrated Coating on the air-to-glass surfaces of the lens elements to minimize the flare and ghosting and enhance contrast. The optical construction features 9 elements in 6 groups, fully automatic diaphragm, 12°20' viewing angle and 52mm filter thread.