I have the chance to acquire, via an exchange with a fellow astronomer, an homemade cassegrain scope. The heart of the scope is a pair of Zeiss mirrors made of Duran 50 glass. The main mirror diameter is 170mm, the focal ratio of the whole system is F/15.
I know there are some 150mm cassegrains from Zeiss, but it is the first time I hear about 170mm mirrors. After an evening spent on Google, I found only an old Astromart ad regarding a similar set of mirrors made by Carl Zeiss Jena (is it ok to post the link here?). It makes sense as Duran 50 is a pyrex made by Zeiss Jena mostly employed in chemical laboratory glassware.
Does anybody have some more background on the history of these mirrors? Their rarity, their quality and when they were produced?
Edited by Marcsabb, 09 January 2019 - 04:37 PM.