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Phyzzx
member
Reged: 02/04/06
Posts: 13
Loc: Utah
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Hi all,
Now that my work life has calmed down quite a bit, i'm eager to get back into the hobby. I pulled out my nearly completed 10" dob project, and realized I had forgotten to purchase a diagonal mirror for it. I went to look up what size mirror I should purchase to compliment the primary in my telescope making book, but I couldn't find it! So, I come to you wise individuals for advice. What size diagonal should I purchase?
Thanks in advance!
Jon
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perfessor
sage
Reged: 12/30/07
Posts: 499
Loc: Northern Illinois
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What's the focal length of your primary? Need to know that.
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Tom
"Don't always know what I'm talkin about"
8" f/7
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Phyzzx
member
Reged: 02/04/06
Posts: 13
Loc: Utah
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Just shy of 48".
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oldtimer
sage
Reged: 11/13/08
Posts: 301
Loc: NW Illinois
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More questions. Whats the OD of the tube? Whats the heigth of the focuser fully racked in? What do you want to use the scope for? Dedicated planetary scopes (high power) can get away with smaller diagonals than RFTs.
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pstarr
Pooh-Bah
Reged: 09/17/04
Posts: 1280
Loc: NE Ohio
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Here is a program to help you figure secondary size. Just plug in your numbers. cilick here
More info
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Paul
10" Home built F-6 Eq Newt. w/Zambuto mirror, built for lunar and planetary viewing.
12'x12' roll-off roof observatory
6" Home built f-6 Newt. w/Dick Wessling mirror on CG-5 Eq. mount, built for high resolution work.
4.5" Orion Starblast on Eq. mount
TV Radians 4,5,6,8,10,12,
Pentax XL 10.5mm
Pentax XW 14mm
Baader Hyperion 17mm
4&5mm UO Abbe Orthos.
3.2mm TMB planetary
TV 2.5x barlow, TV 1.8x barlow
My equipment philosophy... If it ain't broke, fix it anyway.
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GaryS
super member
Reged: 10/30/06
Posts: 191
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Quote:
Hi all,
Now that my work life has calmed down quite a bit, i'm eager to get back into the hobby. I pulled out my nearly completed 10" dob project, and realized I had forgotten to purchase a diagonal mirror for it. I went to look up what size mirror I should purchase to compliment the primary in my telescope making book, but I couldn't find it! So, I come to you wise individuals for advice. What size diagonal should I purchase?
Thanks in advance!
Jon
Hi Jon:
There are a number of things to consider when choosing the "correct" diagonal size. Pop over to my web site and have a look at my article "Sizing Up the Newtonian Secondary." That'll fill you in so that you can make your choice based on your scope's parameters and your own personal inclinations.
Happy reading!
Gary
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Sky & Telescope Contributing Editor
SkyNews Columnist & Blogger
www.GarySeronik.com
A place for stargazing enthusiasts.
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Phyzzx
member
Reged: 02/04/06
Posts: 13
Loc: Utah
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Thanks guys! Sorry it took so long for me to get back and respond. The life of a teacher is always busy. Thanks for all the help and information!
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Cary
Vendor (Optic Wave Labs)
Reged: 07/07/04
Posts: 399
Loc: Rancho Cordova, CA
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I have free diagonal calculator software located here: http://www.opticwavelabs.com/education.html
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Cary Chleborad
http://www.opticwavelabs.com
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