The Tenyu binocular model was one of the very first products that Nikon (then known as Nippon Kogaku K. K.) ever sold, with the product's release coming immediately after the establishment of the company. The Tenyu includes a Porro prism, has an aperture of approximately 30 mm, and boasts a magnification of either 6x or 8x.
Binoculars inherited from the Fujii Optical Works
Nikon was founded in July 1917. That very same year, it took over the development, manufacturing and sales operations of the optical measuring instruments division of Tokyo Keiki (in August), the reflector division of Iwaki Glass (also in August), and the Fujii Optical Works (in December). Binocular sales began the following year (1918).
The Fujii Optical Works was established in 1909 and principally manufactured binoculars. As well as the Tenyu, Nikon also inherited several other brands of binoculars from the Fujii Optical Works—the Asahi (6x15), the Fuji (6x20 and 7x20), the Yamato (6x26 and 8x26), the Sakura (3.5x15), the Nippon (8x26 and 6x26) and the Opera Glasses (3x).
The Tenyu model was manufactured domestically in Japan. However, the lenses and prism were made using optical glass imported from Germany.
One of the founding goals of Nikon was the establishment of manufacturing technology for optical glass. The lenses used in instruments such as binoculars and telescopes are made from optical glass. At the time, however, the technology for manufacturing optical glass did not exist in Japan, and the company had to rely on imported products from Germany. Subsequently, however, the deteriorating international situation made the domestication of optical-glass manufacturing an urgent priority.
In 1918, the year after the founding of the company, Nikon built a test furnace and began manufacturing optical glass, a process it has continued to this day.
MIKRON-the first Nikon binoculars
In 1921, Nikon released its MIKRON compact binoculars. The design and manufacturing of the MIKRON were carried out by Nikon, and in an era in which a number of binocular models were designed, the MIKRON was one of the first models to be manufactured by Nikon. The MIKRON model was highly acclaimed as high-performance compact binoculars. The MIKRON was reproduced and re-released in 1997 as the 6x15M CF, and it has proved a popular model and is still on sale today.
Prototype Nikon binoculars
Of all the binocular models that Nikon inherited from the Fujii Optical Works, the Tenyu was the one whose objective lens had the largest diameter aperture. With the starting salary for a bank employee at the time at around 50 yen a month, the Tenyu was something of a luxury item—the 6x magnification model selling for 90 yen and the 8x magnification model selling for 95 yen.
The picture of the Tenyu is from Nikon's historical archives. The white rubber eyecups are intended to make the binoculars easier to use in the dark. The eyecups of most binoculars are black. Apart from the deterioration of this white rubber, the binoculars are well preserved and can still be used.
The markings "Victor No. 1 x6" and "JOICO" are visible on the metallic section.
"Victor" was the Tenyu's original name. The Fujii Optical Works had used this name when exporting the model to Europe. The use of an English name domestically in Japan attracted criticism and it was subsequently changed to "Tenyu," which means "help from heaven."
JOICO is a trademark made up of the initial letters of the Japan Optical Industry Co., which is a literal translation of Nippon Kogaku K. K.—the company's name at the time.
The Tenyu was used mainly for military and nautical purposes, and was well able to meet such exacting professional requirements. It remains the quintessential prototype for all Nikon binoculars.