Tenax II

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The Tenax II model 580/27 is an advanced 24×24mm on 35mm film RF-camera launched by Zeiss Ikon (ZI) in 1938. Its proper name is actually Tenax, but a much simpler camera with the same name, although with a different body casting, was launched the following year, both designed by Hubert Nerwin. The advanced 1938 model is known as mark II, or just Tenax II, while the simpler 1939 model 570/27, is known as Tenax I. The Tenax name goes back to the C. P. Goerz company in Berlin, using it from 1907 on folding plate cameras. It was used again by ZI in the 1960s. The manufacture of Tenax I was continued for a while in the 1950s in East Germany.

The Camera

The main object of the Hubert Nerwin concept is speed, and both winding and focusing the camera, as well as setting the exposure, is exemplary quick and easy. This is accomplished using a large wind-lever at the right-hand camera front operated downwards by the index finger. It is mounted coaxially to the lensmount, and is sometimes described as a plunger. The shutter-release is just next to the top of the wind-lever in its rest position, enabling fast switching the finger back and forth. The entire concept was patented by Nerwin's team at Zeiss Ikon [1].

The coupled rangefinder image is visible in the viewfinder. It employs two counter rotating sandwiched wedge-shaped prisms, placed in front of the rangefinder window. They are an integral part of the interchangeable lens, and therefore directly geared to the focusing mechanism in the lens barrel. This system is similar to that on the Super Ikonta, the Super Nettel and the Nettax, and it shows to what extreme ZI went to evade the Leica patents.

The behind the lens shutter is a Compur Rapid OS leaf shutter speeded from 1 to 1/400 sec. and B. Time exposure is obtained at B by depressing the shutter release button and rotate it clockwise while depressed. The button is threaded for cable release. The square image format yields 48 images on a standard 36 image length of film.

The Tenax II was certainly inspired by the Robot camera, a small 24x24mm camera with spring-driven motorized film advance, launched in 1934. The format was indeed the same, as well as the emphasis on rapid action shooting. The rangefinder Tenax II was more sophisticated, but it was not commercially as successful, and production ended within a few years, unlike the Robot.

There are Tenax II cameras engraved Luftwaffeneingentum ("Luftwaffe (German Air Force) Property"). A special version for taking pictures of X-ray images on a flouroscope screen, called the Röntgen-Tenax was also made available. It is designed to be handled while wearing thick gloves, and has a metal slide to protect the film from X-rays when not in use.

Tenax II lenses

The lens was interchangeable but only four different lenses were available:

  • Carl Zeiss Jena 4cm f/2 Sonnar standard lens (6612 units[2])
  • Carl Zeiss Jena 4cm f/2.8 Tessar standard lens (4001 units[2])
  • Carl Zeiss Jena 2.7cm f/4.5 Orthometar wide-angle lens (302 units[2])
  • Carl Zeiss Jena 7.5cm f/4 Sonnar tele lens (1026 units[2])

Carl Zeiss also produced some prototypes for the camera (e.g. 4cm f3.5 Tessar, 3.5cm f2 Biotar)[2], which did not make it into general production. The total number of standard lenses (>10.000) indicate a similar production of the camera itself. However, some sources estimate only about 8500 cameras.

Tenax II accessories

  • the close-up Contameter set, in a special version for the Tenax II, with code number 1339. It was sold in a case with a special close-up finder and three close-up lenses matched by three lenses for the finder device.
  • accessory finder for the 2.7cm Orthometar
  • finder mask for the 7.5cm Sonnar, #580/7
  • Albada finder for 4cm and 7.5cm, #433/17


Bibliography, References

  1. Deutsches Reichspatent 666.559 from 9.Jun.1935, Deutsches Reichspatent 660.603 from 18.Jul.1935
  2. 2.0 2.1 2.2 2.3 2.4 Hartmut Thiele, "Fabrikationsbuch Photooptik II Carl Zeiss Jena", 9th edition, Munich 2020.

Links

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