Re: [ATM] ritchey cretians

["Khail Rosenberg" <mikhail.rosenberg@rosenbergtelescopes.com>]

WOW!

I am very appreciative of this group, I Have only been signed up for a few
days and I didnt expect such great support. Thank you all.

With my situation i want to go all in for the first time, I have the
patience i think to perform this project.... My first one is going to be a
48" primary, about half the size of Hubble.. This will be my first RC, but
not first cassegrain.

I believe i will use the flat mirror test for the secondary, using a mirror
flat the same size as the primary, this way i can have multiple 48" mirrors
lying around ?

also a good way to grind a flat is to use three pieces of glass.. one on top
of another, then switch between the three, use and interferometer... then
grind/polish the high spots, it seems like a painful process but as long as
you have about a 4" hand tool to do the polish it is not as bad as it
sounds... this way you also end up with three 48" flats not one.. can make
some good collimators that way, used for comparison against one another.

What i am more puzzled with is the limitation to focal length of the
primary, how fast can you make the mirror? i heard 1.5, I believe there
would be some distortion at that level.. But i also heard people making .9
focal lengths.. Any thoguhts what ideal would be?

the secondary will be about 16" pretty darn big for a secondary :(

I wish to say thanks again for all the emails, and the more the better, but
i have a good starting point.

THanks!
mikhail

On 1/17/08, William Marriott <bmarriott@pacbell.net> wrote:
>
> Hello Khail;
>
> Hello
>
> As 1/2 of the dual 20" fused silica Ritchey-Chrétien
> consortium, I can tell you the best place to get info
> is by searching the ATM list archives, as the topic
> comes up here and there, as well as go to
> Wellman-Bell's website, and order the great book,
> Telescope Optics, Evaluation and Design, by  Harrie
> Rutten & Martin A. M. Van Venrooij, get the software
> that comes with it (added cost) and you will be at a
> good starting place.
>
> The all to often used, some will start, few will
> finish  comes to mind.
>
>
>
>
>
> --- Khail Rosenberg
> <mikhail.rosenberg@rosenbergtelescopes.com> wrote:
>
> > Hello,
> >
> > I am a bit new to the group, and am wondering if
> > anyone has good sites, or
> > has even done a Ritchey Cretian? I am very
> > interested in this project
> > because of how challenging it can actually be.
> >
> > I have been googling for quite some time to find
> > some info on it, but still
> > nothing really shows a step by step on how to make
> > one, test, etc.
> >
> > any help will be greatly appreciated.
> >
> > Thanks,
> > Mikhail
> > _______________________________________________
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> >
>
>
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