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
Petzval Designs

Forum List | Follow Ups | Post Message | Back to Thread Topics | In Response To
Posted by Robert May on June 3, 2001 19:13:22 UTC

Since you are starting with a design for which you don't have the specs it would be wise to do an autocollimation Foucault test with the front lens to find out what it's color error is. Do this with 3 color LEDs is good enough but more colors will help. Generate the curve over the spectrum and you will have a good idea of what you need to correct for in the second doublet.
I might note that the design in that post to the ATM list wasn't all that specific as to the best design but rather is a common design that is fairly appproximate when the glasses aren't fully known. Raytracing will provide the difference between a design which will provide a decent view like a Clark, etc. telescope and the much better view of what you have with your more modern doublet. There's a lot more improvement as you have seen with Nagler's work and, with the modern raytracing software, it's not all that hard to equal his work if you work carefully.
I might also note that there is a "color corrector" design that has been done by the russian importer and have heard some good reviews (reviewers are not really known to me and could be a shill for the guy) of the corrector.
There's a lot of work that can be still done with refractors as the professional industry has gone exclusively to reflectors for their needs and thus have no need to drive the optics designers to do their work with refractors.

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 1994-2020 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