The Nikon was the first camera introduced by the optical manufacturer Nippon Kogaku K.K.. It is a 35mm rangefinder camera, now known as the Nikon I. The original design was approved by September 1946. After over a year of development and testing, manufacture began in March 1948. Sales began in September 1948 with a shipment of 100 cameras to Hong Kong. Production grew slowly over the next year, with all but a few of the cameras being sold to overseas markets including the United States. Because it uses the Zeiss' Contax camera mount, the Nikon camera bears a strong external resemblance to that camera. However, both the shutter and rangefinder mechanism followed the Leica's, resulting in a simpler, easier to manufacture design.
The factory, encouraged by the Japanese government, chose the 24 × 32mm frame size pioneered by Chiyoda Kogaku—known as the Nippon format—which yielded more frames per length of film, and matched more closely the common paper sizes. However, the United States importers, Overseas Finance and Trading Company, objected to this non-standard format. It did not correspond to the automatic slide cutting machines being used in the US, and the images might be sliced in the middle. In addition, the Central Purchasing Office (CPO) that controlled the sales of cameras to the military exchange stores in Japan decided that they would not approve cameras for sale with that format either. Effectively cut off from the two most important markets for their new camera, Nippon Kogaku redesigned the camera's film gate, pressure plate and gearing in August 1949. This became the Nikon M. Introduced in the autumn of 1949, this model can be recognized by the M preceding the body number. The Nikon's body casting and shutter did not permit increasing the format to a full 24 x 36mm. Therefore Nippon Kogaku settled for an intermediate frame format of 24 × 34mm, but did change the gearing to increase the number of perforations per image to the standard 8 (instead of 7 for the 24 x 32), This was acceptable to the export market as slides, although still slightly narrower, were now always cut between frames.
The Nikon M was sold in the PXs, and United States sales resumed, but the camera received little attention in the western media until the fall of 1950, when photographers from the Life magazine began reporting on the Nikkor lenses' sharpness. The Nikkor-P.C 1:2 f=8.5cm received the first attention, but the 5cm f1.5 (later f1.4) and 135mm Nikkors also received praise. A demand to fit Nikkors to reporters' Leicas were immediately met at the factory in Tokyo, and soon the word spread that these Japanese lenses were just as good as, or possibly better than their German counterparts.
In November 1950, Nippon Kogaku made built-in flash synchronization a factory standard.