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: Thanks-got Another Question

Forum List | Follow Ups | Post Message | Back to Thread Topics | In Response To
Posted by Jarvis Krumbein on April 21, 2002 03:48:25 UTC

You really need to get close enough to the knife edge so that the entire surface of the mirror is illumunated. This can be a problem but it is not to difficult to solve. I have a similar problem with a very small blind spot in my right eye so I've always built my testers to use my left eye. The basic design that Tex uses is really rather antiquated and can be improved very easily. This improvement also guarentees that the knife edge and slit are always lined up accurately. It also allows the use of a very small and cool light source, a small flashlight bulb with built in lens. I've been using this version for over thirty years with excellent results. If you are interested in details, e-mail me directly to and I'll send drawings. The only change to the Tex version is that the lamp housing is completely done away with so that it is very easy to use either eye. Another solution is to place a small very low power telescope behind the knife edge so that the objective is almost in contact with the knife edge. The shadows are them examined through the telescope. This has the advantage of much better eye relief and less dependence on the eye position when testing.

Jarvis Krumbein,

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