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Millennium Star Atlas

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#1 pjglad

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Posted 07 November 2012 - 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.

#2 turtle86

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Posted 07 November 2012 - 12:01 PM

Try the Televue Eyepiece Calculator:

http://www.televue.c...d=89&plain=TRUE

#3 pjglad

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Posted 07 November 2012 - 05:40 PM

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

#4 Rick Woods

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Posted 07 November 2012 - 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.

#5 pjglad

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Posted 07 November 2012 - 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.

#6 Rick Woods

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Posted 08 November 2012 - 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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