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
Knife Edge Testing

Forum List | Follow Ups | Post Message | Back to Thread Topics
Posted by Joe/">Joe on May 3, 1999 12:51:07 UTC

I am now finishing and parabolizing my 8" f/8.1 mirror. I have a question about knife edge testing. I think I am doing it wrong.

I set the focal plane to the back of the knife edge test. I can move the knife towards the mirror and cut into the focal point and darken the left side of the mirror. However, I can not darken the right side of the mirror because I can not move the knife back any further. Therefore, it appeared to me that I had a perfect sphere because I was not able to properly cut the knife it to the focal point. Am I supposed to set the focal point of the mirror more towards the mirror so I have more range of movement for the knife edge?

Also, how long does it usually take to parabolize an 8" mirror?

Thanks, Joe

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 1994-2022 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