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Zeiss 170mm F/15 mirror set - any info?

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#1 Marcsabb

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Posted 09 January 2019 - 04:31 PM

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.


#2 Phil Barker

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Posted 09 January 2019 - 05:19 PM

You say they are zeiss how can you prove that.   ie are they marked as such what evidence is there ??

 

I've see a 150mm cassegrain which  had a large  40%ish obstruction how big is the secondary with the 170?  



#3 Marcsabb

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Posted 10 January 2019 - 01:50 AM

About the Zeiss brand? None but the word of the seller. He bought them from another guy who started to build his own telescope with these mirrors, but apparently he never finished the job. According to that Astromart ad, at least he would not be the only one to claim to be in possession of some 170mm mirrors made by Zeiss Jena.

 

Brand aside, the scope has been checked by a third party optician (who also builds premium, hand crafted telescopes of his own design) and according to him the mirrors are of 'very high quality'. At any rate, I would be swapping it with a telescope I rarely use so I'm not risking a lot. I was just curious about the story of these Zeiss mirrors.



#4 Paul G

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Posted 10 January 2019 - 09:45 AM

Marty at Company 7 is a Zeiss historian. Give him a call.



#5 Marcsabb

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Posted 11 January 2019 - 04:23 AM

In a new development, I have discovered that the mirrors may actually be the very same which appeared in that Astromart ads a few years ago! I will try to contact the seller directly.



#6 Peter Besenbruch

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Posted 11 January 2019 - 01:19 PM

In a new development, I have discovered that the mirrors may actually be the very same which appeared in that Astromart ads a few years ago! I will try to contact the seller directly.

Keep us posted.




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