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pjglad
sage


Reged: 01/29/11

Millennium Star Atlas new
      #5508223 - 11/07/12 11:32 AM

I recently acquired the Millennium Star Atlas and the transparent overlays. Overlay 2 contains a variety of circles ranging from 1/4 of a degree to 3 degrees. I have a CPC800 and a CPC1100 plus the following Tele Vue EPs:

Ethos 8
Ethos 10
Ethos 13
Ethos 17
Ethos 21
Nagler 31

Is there a formula I can use to figure out which EP maps into a specific circle size? Thanks.


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turtle86
Pooh-Bah Everywhere Else
*****

Reged: 10/09/06

Re: Millennium Star Atlas new [Re: pjglad]
      #5508268 - 11/07/12 12:01 PM

Try the Televue Eyepiece Calculator:

http://www.televue.com/engine/TV3_page.asp?id=89&plain=TRUE


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pjglad
sage


Reged: 01/29/11

Re: Millennium Star Atlas new [Re: turtle86]
      #5508769 - 11/07/12 05:40 PM

Also, I have a Stellarvue F50 Finderscope. Which circle does that map into?

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Rick Woods
Postmaster
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Reged: 01/27/05

Loc: Inner Solar System
Re: Millennium Star Atlas new [Re: pjglad]
      #5509056 - 11/07/12 09:17 PM

Figure out what the FOV is for the finder, and use that circle (or add one that size). It all depends on the TFOV of each EP/finder.

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pjglad
sage


Reged: 01/29/11

Re: Millennium Star Atlas new [Re: Rick Woods]
      #5509074 - 11/07/12 09:33 PM

Rick, I'm confused. The TFOV is 5.75 degrees and the magnification is 9X. So are you implying that the circle size is greater than the unaided eye Telrad 4 degree circle on overlay 1? Thanks.

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Rick Woods
Postmaster
*****

Reged: 01/27/05

Loc: Inner Solar System
Re: Millennium Star Atlas [Re: pjglad]
      #5509280 - 11/08/12 12:42 AM

Yes. Unless I'm missing something here, 5.75 degrees is 5.75 degrees, no matter what you're seeing it through. The 4* circle describes 4 degrees as seen on the MSA charts. Get another piece of plastic and make a circle proportionately larger than the 4* circle, and that'll show the same area on the charts that you'd see in your finder. The true FOV size is the common factor.
Degrees is degrees!


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