Ultra rare, fast and exceptionally sharp micro lens. A real rarity. "As Nikon stated it in an early '80 sales catalogue: - Although developed primarily for the production of photomasks for high-frequency semiconductor elements (diodes, transistors, ICs and LSIs), Ultra-Micro-NIKKOR lenses were useful in other applications such as photo-etching, for production of evaporation masks by electroforming and of photommasks of filter, mesh or other minute parts and for direct projection printing of photomarks onto plates coated with photo resist. Ultra-Micro-NIKKOR lenses were also an ideal choice for making lens testing charts and producing glass plates on which complex micro-patterns for optical instruments or even inspection equipment are printed. Another important application was for ultra-micro photographic reproduction of books, company documents and literature etc. as ultra-microphotography provides practical solution for those who may require to handle vast volume of data occupying a minimal amount of space such as microform of microfilming and microfiche. The lenses were also useful for those computer systems which require ultra-high density storage of information One additional application them were for use in testing resolving power of everyday film. As the Serial Number progresses to this particular unit a red M with R=Ratio (M=1/10) has been included at the lens data ring. With f/1.8, this relatively unknown Nikkor 28mm can claimed to be the fastest 28mm wideangle made by Nikon until 1993 with the debut of AF Nikkor 28mm f/1.4D"