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
Size

Forum List | Follow Ups | Post Message | Back to Thread Topics | In Response To
Posted by Robert May on November 4, 2002 22:05:14 UTC

As you go towards larger diameter refractors, you also run into a problem with getting glass as well as needing longer focal ratios to keep the color problems in control. Remember that as the aperture increases, the Airy Disc size decreases and as a result, the color error grows more obvious.
I'd stick with the 8" size (this from a guy that has a set of glass for a 12" on hand!) as a good max size for the amateur as this size will keep good color in the image.
Before you actually start grinding, use the exact glass indicies and do a good raytracing to get the exact radii that will minimize the color error. The software that comes with the Rutten and Van VenRooij book "Telescope Optics" is a nice cheap raytracer that will work well as well as some of the freeware stuff that is out there. Oslo LT is available but it is a rather complex piece of software to use.

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 1994-2024 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