The Nikon Micro Nikkor 55 mm f/3.5 (non-Ai type-F) is a normal prime macro lens for 35 mm Nikon F SLR cameras.
Without extension tubes the Nikon M makes it possible to take 1:2 macro scale pictures (1:1 with extension tubes).
From 1961 to 1963 the Nikkor 5.5cm/3.5 Miсro lens was being produced featuring the same 5/4 optical scheme, but slightly different size and weight. It was equipped with a 7-blade aperture. Since1969 the lens featured a different 5/4 optical formula.