ATM Forum Message | |
| Forums: |
Atm ·
Astrophotography ·
Blackholes ·
Blackholes2 ·
CCD ·
Celestron ·
Domes ·
Education
Eyepieces · Meade · Misc. · God and Science · SETI · Software · UFO · XEphem |
|
|
|
|
||||
|
|
||||||
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. |
|
| 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 |