Louwman Collection of Historic Telescopes Arrow right Arrow left

photo - eyepiece
Basic Info

Maker: Unknown


Year Range: 1784-1786

Year Notes:

Manufacturing Location: Japan


Signature Notes:


No stand present.

Collection: Louwman Collection of Historic Telescopes

Accession #: LC 256


Project investigation.

Louwman, P.J.K., and Zuidervaart, H.J., "A Certain Instrument for Seeing Far: Four Centuries of Styling the Telescope Illustrated by a Selection of Treasures from the Louwman Collection of Historic Telescopes". Wassenaar, 2013. p.187. #256.

Public Notes:

"Japanese telescope. Red lacquered main tube, with three black lacquered drawtubes signed by Iwahashi Zenbei. Length 230 cm, Ø 9.5 cm. Marked in Japanese characters: ‘First month of the year of the Dragon’ (which is 1784 or 1796). With rectangular wooden case.
Iwahashi Zenbei (岩橋善兵衛, 1756–1811) was a Japanese scientist and optician. He was born in Kaizuka, Osaka in the merchant family ‘Iwahashi’. He was trained in science and optics by Minagawa Kien, a scholar in Kyoto. In 1793 Zenbei made his first telescope, after he had investigated some imported specimens. This telescope with an octagonal tube, a length of 270 cm and a diameter of 27 cm went to the astronomical observatory of the Shogun, founded in 1787. Zenbei’s telescope was regarded as being of comparable quality as the models imported from Europe. Iwahashi made also telescopes for the cartographer Ino Tadataka. Iwahashi regularly observed the sun, the moon and the stars. In 1801 he developed an instrument to calculate the movements of celestial bodies and tides, called ‘Heitengi’ (平天儀). A year later he published book on astronomy , called ‘Heitengi zukai’ (平天儀図解). The asteroid 7538 Zenbei (discovered in 1996) was named after him. The descendants of Iwahashi Zenbei became telescope makers for four generations" (Louwman and Zuidervaart, 2013).

Length (open):

Length (closed):


Exit pupil:

Object status:

Optical Basics

Objective type: unconfirmed

Optical style

Physical style

Functional style

Materials: wood, glass, lacquer, gold tooling, horn

Optical/Lab Data

Drawtube data:

Drawtube notes:

Objective Data