Lichtenknecker optics 300mm dual focus telescope: Newton or Cassegrain
We’re still trying to figure out all the details of this telescope, at this point we only know it’s diameter (300mm), focal length of the primary mirror (approx. 1620mm, according to our measurements and the numbers written on the back of the primary mirror) and the fact that both secondary mirrors are present AND can be installed. But no focusing mechanism available, neither at the Newtonian focus nor at the Cassegrain focus.
The mirrors are still in great shape, it seems the telescope tube stayed always carefully closed while packed inside the house.
Update 09/2023: I was able to determine the focal length of the Cassegrain-configuration (by measuring the size of the Solar disc in the focal plane! Be careful if you try this at home :-)) => approximately 7.700mm (+/- 200mm). So it seems to be an f/25 – or slightly longer.