Y.K. Optical
Y.K. Optical
Y.K. Optical was a small Japanese lens maker or optical business based in Yokohama and active in the modern revival of Leica screw-mount rangefinder lenses. It is associated with compact wide-angle lenses sold under the Avenon, Kobalux, and Pasoptik names. The best-known product is the 28mm f/3.5 Wide lens, a rangefinder-coupled LTM design intended for Leica, Canon, Voigtländer, and other compatible cameras.
History
Founding / Early Years
No authoritative public record gives a precise incorporation date or full corporate history for Y.K. Optical. Specialist accounts describe a very small Yokohama operation. A reported connection between its founder and the earlier Sankyo Kohki or Komura organization is plausible but not documented strongly enough to present as settled fact.
Market Entry
Y.K. Optical's compact 28mm f/3.5 was available by the mid-1990s, when renewed interest in classic rangefinder photography created a market for new LTM lenses. The same basic lens was distributed under different regional names, including Avenon in Japan and Kobalux in the United States. A 21mm f/2.8 wide-angle lens followed, extending the range beyond the 28mm model.
Expansion / Modern Period
Specialist histories place the main production period at roughly seven years from the mid-1990s and report that manufacture ended in February 2002. The company did not become a large optical group, and its lenses remained limited-production alternatives to Leica, Canon, and Cosina Voigtländer products. There is no documented current Y.K. Optical rangefinder-lens program.
Product Lines
28mm Rangefinder Lenses
The 28mm f/3.5 was sold under Avenon and Kobalux branding, with changes in coating, diaphragm, and minimum focus across production versions.
21mm Rangefinder Lenses
The later 21mm f/2.8 provided a faster ultra-wide option in Leica screw mount.
Technical Characteristics
| Feature | Description |
|---|---|
| Manufacturing base | Yokohama, Japan |
| Reference lens | Wide 28mm f/3.5, sold principally as Avenon or Kobalux |
| Lens mount | Leica M39 screw mount, LTM or LSM |
| Optical construction | Six elements in four groups for the 28mm f/3.5 |
| Production changes | Early and later versions differ in coating, diaphragm, and close-focus specification |
| M-mount use | Designed to work with an appropriate LTM-to-M adapter |
Market Reception
Y.K. Optical lenses are appreciated for combining true rangefinder coupling, compact construction, and modern coatings with the classic Leica screw mount. The 28mm f/3.5 is especially valued as a lightweight travel and street-photography lens. Production variants and multiple distributor names can complicate identification, so cataloguing should record the exact front-ring brand, serial number, coating, aperture-blade count, and closest-focus marking.
Sources
Lenses (0)
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