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Astrophotography and Sketching >> Sketching

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moonzero2
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Reged: 07/30/08

Loc: Elizabeth, Colorado
Re: Sketch of Jupiter on 9-19-10 at 4 UT new [Re: Sarkikos]
      #4104422 - 10/09/10 10:38 PM

Great Sketch!
I definitely need to make me an apodizing mask.


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Sarkikos
Postmaster
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Reged: 12/18/07

Loc: Nyctophobia, Maryland, USA
Re: Sketch of Jupiter on 9-19-10 at 4 UT new [Re: moonzero2]
      #4105265 - 10/10/10 12:29 PM

Bob,

Thanks. An apodizing mask is pretty easy to make. I made mine from some aluminum screen I had in the attic, black foam core and Gorilla Glue. Sandwich the three rings of screen between two rings of black foam core. The screen I had available was shiny aluminum, but I went over it several times with black permanent marker. Metal screen is stiffer and so doesn't distort in shape as easily as other materials.

An apodizing mask should work great with your 12" Newt. Don't let anyone talk you into making an aperture mask to stop down your telescope. Why pay for all that aperture and deal with the extra weight just to end up stopping it down? It doesn't make sense. An apodizing mask will increase contrast but not appreciably reduce resolution, especially if you observe from a seeing-challenged area. Do a Google search and try to find a formula to let you figure out the ID of the three rings for a 12".

Clear & Steady Skies,
Mike


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Sarkikos
Postmaster
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Reged: 12/18/07

Loc: Nyctophobia, Maryland, USA
Re: Sketch of Jupiter on 9-19-10 at 4 UT new [Re: Sarkikos]
      #4105421 - 10/10/10 01:38 PM

Bob,

Check out this website. This is where I got the info to make my apodizing mask, though I changed the materials used. I didn't like the idea of having wood and screws hanging over my primary, and I thought a metal screen would be sturdier than fiberglass. It does give percentages of primary aperture for your screen rings: 1st screen 90%, 2nd screen 78%, 3rd screen 55%.

A Do-It-Yourself Apodizing Mask

Suiter has a website which gives charts of technical specs, but it is hard going. I'm afraid if I had only looked at that website, I still wouldn't have an apodizing mask! Just give me some rules of thumb and let me get to work!

Mike

Edited by Sarkikos (10/10/10 01:39 PM)


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moonzero2
member


Reged: 07/30/08

Loc: Elizabeth, Colorado
Re: Sketch of Jupiter on 9-19-10 at 4 UT new [Re: Sarkikos]
      #4110457 - 10/12/10 03:04 PM

Mike,
Thanks a million!
Looks easy enough.
Need to make one right away while Jupiter is here visiting us.
I'll let you know how it works out.
Bob


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Sarkikos
Postmaster
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Reged: 12/18/07

Loc: Nyctophobia, Maryland, USA
Re: Sketch of Jupiter on 9-19-10 at 4 UT [Re: moonzero2]
      #4110900 - 10/12/10 06:21 PM

Bob,

The apodizing mask should definitely add contrast to your view of Jupiter. I wouldn't be surprised if it will have a more dramatic effect on your 12" Newt than it has had on my 10". It really does make more sense to use an apodizing mask than to stop down your aperture. The "glare" is not the problem when observing planets. That can be corrected by using a binoviewer, keeping your eyes photopically adapted and - if you must - using filters. (The Baader M&SG is the best all-around planet filter, IME.) The real problem is lack of contrast. The apodizing mask will improve that. We can't do much about the seeing, except maybe move to south Florida!

Let me know how the mask works out for you.

Mike


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