Back to Home

ATM Forum Message

Forums: Atm · Astrophotography · Blackholes · Blackholes2 · CCD · Celestron · Domes · Education
Eyepieces · Meade · Misc. · God and Science · SETI · Software · UFO · XEphem
RSS Button

Home | Discussion Forums | Amateur Telescope Making | Post
Login

Be the first pioneers to continue the Astronomy Discussions at our new Astronomy meeting place...
The Space and Astronomy Agora
Secondary Size Might Be Wrong - Need Help Urgently

Forum List | Follow Ups | Post Message | Back to Thread Topics
Posted by Dave Sellors on May 26, 2003 16:43:09 UTC

I've almost finished building a 10" dob (Richard Berry book), my first time doing this stuff. Mirror is 10" F/5, secondary size is 1.83" I laid out optics using Newt 2.5 and did ray trace using Visio. Newt reported everything to be fine (no YES's). The focuser hole location was based on achieving a very thin, almost imperceptible, black ring around the primary when looking at the secondary mirror through the focuser.

I now have just read "treatise on newtonian collimation", which seems to say I should have a somewhat thicker black ring.

What should I do ? Advance the mirror toward the secondary and hope focuser height can absorb it, or should I get a 2" secondary.

Follow Ups:

Login to Post
Additional Information
Google
 
Web www.astronomy.net
DayNightLine
About Astronomy Net | Advertise on Astronomy Net | Contact & Comments | Privacy Policy
Unless otherwise specified, web site content Copyright 1994-2020 John Huggins All Rights Reserved
Forum posts are Copyright their authors as specified in the heading above the post.
"dbHTML," "AstroGuide," "ASTRONOMY.NET" & "VA.NET"
are trademarks of John Huggins