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Old 16-02-2019, 05:55 PM
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sopticals (Stephen)
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Join Date: Jun 2010
Location: Oamaru, New Zealand.
Posts: 226
Any body out there?

Hi guys, you got any new mirror grinds on "the make"?

I've been so enjoying the full 2 degree wide views of Milky Way with my 10" Zhumell (one of my two "grab and go" scopes) using a Nagler 31T5 that for a "more intense" experience at the 1200-1250mm focal length I have decided to grind out a 12 1/2" blank I have sitting spare, to approx f4. Exit pupil at the 40.3x is close to 8mm, but my dark adapted pupil opens pretty wide at 7mm plus so won't lose much light.

Have played with 6"f8, 8"f6, 10"f5 (all around 1200-1250mm fl) so why not try 12.5" f4 for the same size FOV?

Anyway started the project today. See picture.
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