10 replies to this topic

[novalab]

I am doing some work on optically modifying these two OTAs, and desperately  need these.

 

I'd appreciate it if you can share the files with me. Alternatively if you have a copy of "TELESCOPES, EYEPIECES AND ASTROGRAPHS" BY GREGORY HALLOCK SMITH, I believe the designs are there, so you could PM me those couple of JPGs so I can create them myself.

 

I would very much appreciate your help with this.

[novalab]

Anyone???

[MitchAlsup]

The C8 model is in ATMOS

[Argonautt]

This article takes data for an 8 inch f/10 Schmidt Cassegrain from Telescopes, Eyepieces, and Astrographs, but doesn't give the page number. It also describes how 

 

the Spherical Mirror 3D part is used to create the primary and secondary mirrors

And as far as this flyer suggests, the LX200 being "Advanced Coma Free" optics design has a spherical primary and hyperbolic secondary - so not the one in the article.

 

So what's the point in this post... well, there isn't much info on the book out there, so if it checks one box off..

Edited by Argonautt, 09 April 2023 - 09:04 AM.

[jimhoward999]

Here is an approximation of a c8.  Unfortunately you cannot attach zemax files, so I just took a screen shot.  The exact prescription is proprietary I believe.  If you are modifying your C8 then you have access to the exact dimension which you can measure when you take it apart.  The you can get more exact values with an optimization run.

 

If your modification just involves not disassembly, but just adding optics to the back end, then this model should be close enough. 

 

Nothing magic here, and no inside information.  I am sure you could do this reverse engineering just as well or better yourself.

 

I don't think the book you mentioned is currently available.

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[novalab]

Thanks for all your feedback. Much appreciated! I knew that this was the right place to ask.

 

I can work with Atmos or OSLO models, and convert to Zemax. 

 

Reverse engineering these scopes is not hard and there is lots of available data out there, but the problem I have is with properly modeling the corrector plates surfaces. This is why I need the models.

 

I have all these scopes in classical forms (C8, C11 & LX200-8" in duplicates), and an not using them. I want to mod, at least the Celestrons, for a particular remotely operated task... thus the optics mod, which will include adding some optics to the baffle tube, and replacing the secondary with a mirror coated achromat lens (on the back) - at least want to model it and see if it will work for me.

 

Any info on C11? That is the one that would be my primary target. C8's will be just for principle testing.

 

While back I found a discussion on extended tube C8, C11 and LX200, showing the improvements. The post had comparisons to standard scopes, and provided screenshots of the OSLO models. I almost killed myself by looking for it, but simply can't find it. I could have sworn it was on CN. Anyone seen this...?

[Oregon-raybender]

The book on "Telescope Optics" by the Rutten and van Venrooij, has details of a SCT in Chapter 9

It should be helpful to you.

 

Starry Nights

[novalab]

Thanks Oregon-raybender,

 

I have the book and use it often. I looked in just in case, and close but no cigar...

 

I wish I could find where I saw it earlier. It had C8/11/14 and LX200-8/10... I can't believe I didn't save it.

[novalab]

Thanks Jim - that is helpful. No, my mod involves changing the secondary and adding optics in the baffle tube.

 

Let me know if you have anything on C11 classic.

[jimhoward999]

Thanks Jim - that is helpful. No, my mod involves changing the secondary and adding optics in the baffle tube.

 

Let me know if you have anything on C11 classic.

It would be the same thing for a C11, just a reverse engineering approximation.    My guess is that even if you found the elusive files that you are remembering, they also would be somebodies very close approximation.    I think the only place you could get the exact prescription is from Celestron itself.....if they would share it with you.

 

I am sure Starzona also has the exact prescriptions.  They would have to in order to design the Hyperstars.

[novalab]

Unlikely that Celestron would share the exact details. They would probably provide the Zemax black box design, which is not useful for what I am trying to do. This is probably what Starizona used since they only added stuff to the OTA, and could not share it as they are certainly under NDA.

 

I'm actually considering measuring the corrector plate surface profiles with a LVDT probe... I can profile the depth with about 1um accuracy, but it is a lot of work to setup, and my time is limited - but that said I could then publish my results (i.e. the complete designs) in the open. 

 

I really wish I could find TELESCOPES, EYEPIECES AND ASTROGRAPHS to buy, or at least someone who has a copy.