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: Knife Edge Testing

Forum List | Follow Ups | Post Message | Back to Thread Topics | In Response To
Posted by Robert May on May 6, 1999 18:30:52 UTC

Make your Couder Masks, do the calculations for what the measurements should be for a parabola and do the measuring in a dark room so you can see the shadows well. You may be making a hyperbola and don't know it until you do the measuring. Don't worry about the exact FL of the mirror (let the hole fill the mirror if that is what it wants to do) but rather get the shape correct. Remember that the longer and wider the stroke is, the more it will cause the center to deepen. If you post again, I'd like to see the numbers and what you have recently measured - include the size and Radius of Curvature of the mirror.

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 1994-2022 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