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The Durax (デュラックス) are Japanese leaf shutters made by Rokuoh-sha, then by Konishiroku (predecessors of Konica).

Zeus and Durax in #0 size

The large model, in #0 size, was first introduced in 1933 as the Zeus (ゼウス), a name only known on advertisements for the Year-Eight Idea and Year-Eight Pearl. It was quickly renamed Durax, perhaps because the brand name "Zeus" was already registered by someone else. It was copied on the German Ibsor.

The range of speeds is T, B, 125, 50, 25, 10, 5, 2, 1. They are selected on a dial at the top, and the release lever is attached to the front face. The shutter is everset, with no cocking lever. The RK logo of Rokuoh-sha is directly engraved on the front face, and the Durax name is inscribed on a separate plate with the aperture scale, attached by two screws. There is a thread for a cable release on the side, on a small hole near the logo, for a thread and needle release (a crude replacement for a self-timer).

The regular Durax in #0 size was mounted on the following cameras by Rokuoh-sha (not all the versions have this shutter):

A later version was mounted by Rokuoh-sha in 1939 on the Sakura-flex TLR prototype. The speeds are set by turning the rim, and the range is slightly extended: T, B, 150, 100, 50, 25, 10, 5, 2, 1. The internals are certainly quite similar to those of the previous version: the position of the release lever and cable release thread is unchanged, and there is no setting lever. The obsolete thread and needle release is replaced by a true self-timer, controlled by a lever placed opposite the release lever and shaped as a scythe. The front face is similar to that of the early Durax in #00 size, mounted on the silver Semi Pearl.

It is reported that some #0 Durax were mounted on the Elliotte 6×6 pseudo TLR, distributed in the early 1950s. Its manufacturer surely re-used old parts disposed of by Konishiroku.

Durax in #00 size

The Durax was released in #00 size at the beginning of 1938 for the 4.5×6cm Semi Pearl, in combination with a Hexar lens. The speeds are set by turning the rim, and the nominal top speed is slightly slower: 1, 2, 5, 10, 25, 50, 100, B, T. The shutter has a setting lever at the top and a release cam at the bottom, and is suited for cameras with a body release. There is a thread for a cable release on the side, towards the bottom, and no self-timer device.

The production of the original #00 Durax was resumed after 1945. Three different front plate designs are known on the Semi Pearl. The same shutter was mounted on the Pearl (I) in 1949, with yet another front face.

Durax-S, #00 size

The name was re-used on the Durax-S, released in 1955 on the Pearl IIB and certainly having a completely different design. The range of speeds is much extended (B, 1, 2, 5, 10, 25, 50, 100, 200, 400) and flash synchronization was added via a PC connector. (The letter "S" in the name surely stands for Synchronized.)


In Japanese: