Try searching for a "Zeiss Tele Tubus". I've got one, used it with a 9x12 camera. The tube needs a tele-negativ cell in the back plus your lens of choice in the front, often a Tessar or Protar. Some tubes have a focussing helical, others not. All the information to figure it out is in one page of some of the 30s Zeiss catalogues. The 45cm Magnar was another oddity from that era.
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