Misuzu Kogaku Altanon 5cm f/2

Misuzu Kogaku Altanon 5cm f/2

The Altanon 5cm f/2 is an obscure Japanese standard lens from Misuzu Kogaku, built in the Leica thread mount (M39 / LTM) during the period when many small Japanese optical firms supplied screw-mount optics for rangefinder bodies. It is one of the lesser-documented 50mm f/2 designs of its era, and verifiable published material on the lens is scarce. What is recorded is its basic configuration: a six-element design arranged in three groups, a maximum aperture of f/2 stopped down by a nine-blade diaphragm, a 41 mm front filter thread, and a closest focusing distance of about 1 m.

As an LTM lens it threads onto Leica screw-mount bodies and, with an adapter, onto Leica M and mirrorless cameras. The lens is not rangefinder coupled and carries no six-bit coding, so focusing on a coupled rangefinder body cannot be confirmed through the camera's mechanism and is best handled by scale or, on mirrorless cameras, by the live image. The six-element, three-group layout is consistent with the double-Gauss-derived formulas common to fast normal lenses of the 1950s, though the specific optical design and any coating details are not well documented in accessible references.

Documentation of production variants, finishes, and serial-number ranges for the Altanon is limited, and no major factory special editions are widely recorded. Because so little is published, prospective buyers should treat individual examples on their own merits rather than relying on a settled body of collector literature.

Optical qualities

Rendering Reliable, repeatable accounts of this lens's rendering are not available in accessible sources, so its character cannot be described with confidence. As a fast six-element normal lens from the 1950s, its general behavior would be expected to follow the conventions of double-Gauss standard optics of the period, but no specific, sourced claims about its sharpness, contrast, bokeh, flare resistance, distortion, or vignetting can be substantiated here, and none are made.

History

Development and Launch The Altanon 5cm f/2 belongs to the wave of screw-mount standard lenses produced by smaller Japanese makers during the 1950s, when the Leica thread mount was a common interchange standard. Beyond its identity as a Misuzu Kogaku product in LTM, detailed and corroborated historical records for this particular lens are not readily available, and firm launch and production-end dates cannot be confirmed from accessible published sources.

Collector Notes Because the Altanon is rarely documented, buyers should verify the obvious physical points directly: clean glass free of significant haze, fungus, or separation; a smooth focusing helicoid; and an aperture mechanism that operates cleanly across its range. Confirm that the example is genuine LTM and that the threads engage properly with the intended body or adapter, and check the 41 mm filter thread when sourcing filters or hoods, as that diameter is less common than the 39 mm and 40.5 mm sizes used by many contemporaries.