Koho

Koho (Kōhō) was the name of the first leaf shutter made from 1936 by Olympus. All the Koho versions had a selftimer and were in #0 size. Francesch says that it was inspired by the German Prontor II. The Koho was mainly mounted on the Semi Olympus and Olympus Six, but Takachiho also sold it to other makers.

Versions and Olympus cameras equipped

The original name of the Koho shutter was Laurel (ローレル, rōreru). It had 1-2-5-10-25-50-100-150-B-T speeds. The first version of the Semi Olympus II (off-centered finder) was advertised with a Laurel shutter in the Oct 1937 issue of Asahi Camera and in a 1937 brochure available at this page of the Olympus corporate site. The book by Francesch and the Olympus Photo Club history pages both indicate that the name "Laurel" was dropped because it was already registered, and the latter pages also mention the existence of the transitional name "Dauled".

The first version of the Koho had 1-2-5-10-25-50-100-150, B, T speeds and was similar to the Laurel. It had the winding lever at the top right, the release lever at the top left, the selftimer lever with a red dot at the bottom left and a soft release screw at the left. It was mounted on a Semi Olympus I variant and on the second version of the Semi Olympus II.

The second version had the same controls and a top speed of 1/200. It has been observed on some Semi Olympus II (see for example here).

The third version had the same 1-2-5-10-25-50-100-200, B, T speeds, but its controls were different, with the winding lever at the top left, the selftimer lever with a red dot at the bottom left, and the release also at the bottom left, activated by a body release. The aperture setting was moved to the top of the shutter housing. It was mounted on most variants of the Olympus Six. In some advertisements for the Olympus Six the shutter is sometimes called Koho II or Koho III (for example in a brochure available at this page of the Olympus corporate site).

Other cameras equipped with a Koho shutter

This list is incomplete.

• first version
  • V Semi First (with a First Anastigmat 7.5cm f/3.5 lens)
  • Semi Kelly
• second version
  • a New Semi Condor, seen at a Yahoo Japan auction. It had what looks like a complicated linkage to a body release.
• third version
  • a Mamiya Six III pictured in McKeown
  • a Zeitax with a folding optical finder and a Zeitax Anastigmat 7.5cm f:3.5 lens (see here)
  • the Sintax
• unknown version
  • Semi Proud II (Baldax copy)

On all the above cameras except perhaps the Sintax, the shutter plate is marked Olympus Tokyo N. This plate has a cut for an aperture scale placed at the bottom, and it does not fit very well with the third version of the Koho. The Sintax has a SINTAX marking at the bottom of the shutter plate, probably filling the cut.

The Kōhō name

The name Kōhō was written コーホー in katakana, but it was apparently formed from the word 高峰, that means "high peak" or "high mountain". This is a clear allusion to the Olympus name (itself from Mount Olympus).

Bibliography

• Francesch, Dominique and Jean-Paul. Histoire de l'appareil photographique Olympus de 1936 à 1983. Paris: Dessain et Tolra, 1985. ISBN 2-249-27679-X.

Links

• Olympus history pages at the Olympus Photo Club website, with exhaustive information:
  • The Semi models
  • The Six and Chrome Six models
• A page at the Olympus corporate site, with links to brochures of the Semi Olympus II and Olympus Six, in pdf format