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Equipment Discussions >> Cats & Casses

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Carpal Tunnel

Reged: 11/04/06

Loc: Cincinnati Ohio
Re: Maks VS SCTs new [Re: Jeff B]
      #5603024 - 01/03/13 01:37 PM

Hey buddy, Happy New Year!..tomorrow evening look promising for Hisey.
Any chance.

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Carpal Tunnel

Reged: 01/06/04

Loc: Toronto, ON, Canada
Re: Maks VS SCTs new [Re: bcuddihee]
      #5603634 - 01/03/13 08:04 PM

That was the first thing I thought of when I saw the image. I've heard of this on some newtonian mirrors, but had never seen these images before from SCT's.

I've never noticed anything on my C14 Edge sample.

Clear skies,

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Reged: 11/02/06

Loc: Latitude 47
Re: Maks VS SCTs new [Re: Jeff B]
      #5605269 - 01/04/13 05:39 PM



What is that strange radial spider pattern on the 2004 c11? I have seen this on one other c11...

And whose C11 might that be ?

Yeah I figured it out last week when I was looking at pictures of a disassembled C14 and noticed the ribs on the back of the mirror. Also, as the mirror cools, those ribs will probably show themselves as well. I notice in my C11 they're much less visible but still there and fairly easy to see even after the scope has stabilized thermally . I catch a very faint hint of them in the C14 as well but I never would have gone looking if I had not seen the photo of the back of the C14 mirror.


From what I've read, it's nothing to do with the primary but an imprint into the corrector's figure from the grooves in the master block used to facilitate the vacuum. Apparently Celestron later changed their master blocks to avoid this problem. Used to be fairly common, even seen in-focus, in the older Celestrons. Newer Celestrons don't have it.


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