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What is a Type A Zeiss apo?

Started by pkelly, 12/13/2005 03:34PM
Posted 12/13/2005 03:34PM Opening Post
Interesting to see Markus Ludes advertize the lastest astro goodie...6" f/17 Zeiss Planetary apo Refractor...doublet Type A apo. I had read the design a long time ago but have forgotten. What is a Type A apo?

8" f/12 D&G classic refractor
Astro-Physics 1200 DA equatorial mount
BlueStar Observatory (roll off) by Backyard Observatories of Lodi, Ohio
Previous telescopes A-Z...Astro-Physics to Zeiss
Posted 12/13/2005 03:57PM #1
There is some detailed discussion of it about 1/3 down
the page at
http://alice.as.arizona.edu/~rogerc/chapters/Chapter%204a.html

Seems a Fraunhofer-like design with light barium crown
and some abnormal short-flint.