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
At The Field Stop

Forum List | Follow Ups | Post Message | Back to Thread Topics | In Response To
Posted by Walter Hamler on September 25, 2001 17:28:17 UTC

The light cone comes to a focus in the focuser at a point where the eyepiece can "look" at the image and magnify it for your observation. That point will be at the field stop of the eyepiece. Not every eyepiece has one, but in those that do it forms the sharply defined edge of the circular eyepiece field. You will note that with longer fl eyepieces the field stop is a greater distance from the eyelens, the shorter fl eyepieces it is much closer, maybe only a few mm's below. Since the shorter fl eyepieces require more "in" travel to obtain focus (place the field stop at the focus), as well as certain designs require more "in travel", it is a good idea to allow for variations, hense the additional 0.5" in travel in the formula. Hope this helps.

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