FOREWORD
An updated version of Nikon's reknown close-focusing lens, the Micro-Nikkor 55mm f/2.8 features a larger maximum aperture. Thus, the image in the viewfinder is brighter and it's easier to focus when the light gets dim or extension rings or a bellows unit are attached. It has a modified Gauss-type optical design of six elements in five groups and incorporates a floating element system in the rear lens group for improved performance. In fact, this lens produces excel- lent image quality at high magnification ratios as well as normal shooting distances, because definition and distortion-correction remain virtually unchanged over the entire focusing range. Nikon's multilayer coating on air-to-glass surfaces also provides significant gain in image contrast and minimum flare at wide apertures. With a built-in dual-helical system, the Micro-Nikkor 55mm f/2.8 focuses continuously from infinity down to a reproduction ratio of 1:2 with the lens focusing, ring. And by attaching the optional PK-13 Ring or TC-201 Teleconverter, it goes from 1/2 reproduction ratio down to 1:1 (lifesize).
