The very impressive 5cm f/1.1 Nikkor-N lens was announced in February 1956 and was exhibited in Tokyo. The 5cm f/1.1 was a very radical lens for its time, consisting of nine pieces of glass, some of which were very thin split elements and others containing rare earth components. This stunning f/1.1 lens would reign supreme as the fastest lens made by the big four 35mm rangefinder camera makers, until the Canon 50mm f/0.95 lens was introduced in the early 1960s. The 5cm f/1.1 Nikkor-N weighed 12.25 ounces (355gm) and it could be stopped down to f/22 with click stops. It used a 12-blade diaphragm and had an angle of view of 46 degrees and a focusing range of 3ft (0.9m) to infinity. The first version of this lens had an internal mount the same as that found on their normal slower range of lenses, and is known as the ‘Internal Mount f/1.1’. However, this lens was so heavy, that its weight could distort the camera mount and cause rangefinder error. This engineering problem was overcome in June 1959, when a 5cm f/1.1 lens was released with a redesigned barrel with an external mount, such as those found on the wide-angle and telephoto Nikkor lenses. The optical formula is identical to the internal mount version and both lenses used the same 62mm accessories and only the rear cap differed.
Factory records state that 1,046 internal mount lenses were made (835 in Nikon bayonet mount and 211 in Leica screw mount) and 1,547 of the external mount version. The 5cm f/1.1 stands as one of the most impressive looking lenses made by Nikon and is certainly one of the most sought-after by collectors. This example is an external mount version.