Technical specificationsThe Zeiss refractor with a lens diameter of 200 mm and a focal length of 3000 mm - built between 1909 and 1911 - is considered by experts to be a rarity, since only six of these devices existed. Carl Zeiss Jena developed a wide range of astronomical observation devices during this time.The main feature of the Ardenne refractor is a so-called E-lens with the Fab.-Nr. 16810. It concerns a classical Achromat after Josef Fraunhofer for color error correction, opening ratio 1:15. As usual at this time, the automatic tracking of the refractor was done by a mechanical hourly mount. The accuracy of these works was excellent and enabled not only the visual observation but also the photograph of the starry sky. During the 2007 restoration, the mechanical hourly drive was replaced by a state-of-the-art electronic stepper motor controller.Source and further information can be found at:
October 15, 2017
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