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

Be the first pioneers to continue the Astronomy Discussions at our new Astronomy meeting place...
The Space and Astronomy Agora
RE: Appendix

Forum List | Follow Ups | Post Message | Back to Thread Topics | In Response To
Posted by Kip Crawford on October 17, 2000 14:37:48 UTC

A good 4.5" reflector should be at least a f/9 ratio which is a 39.5" focal length. At f/4 or 5 which is between 18" to 25" (short tube, fast focus). The reflector uses a primary mirror that reflects the focus to a 45 degree secondary mirror that goes to the eyepiece. Quite simple really. The more elaborate type scope is the Schmidt-Cassegrain (SCT) which uses a corrector lens which enables the scope to have a long focal on a short tube.

Follow Ups:

Login to Post
Additional Information
About Astronomy Net | Advertise on Astronomy Net | Contact & Comments | Privacy Policy
Unless otherwise specified, web site content Copyright 1994-2023 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