Re: ATM Re: [APML]: Rumak design experiences ?

[Bill Lee <wlee@ix.netcom.com>]

Frank Schiralli, Jr. wrote:

> At 09:52 PM 1/11/99 +0100, you wrote:
> >The Astro-Photography Mailing List
> >------------------------------------
> >
> >Hi Guys !
> >
> >Anyone here on the list who has got some experience with the Rumak
> >Maksutov-Cassegarain design which Harry Rutten et al published in his
> >book 'Telescope Optics'? I already know that it is build by a guy in
> >Ontario, Canada (Telstar) in a tiny series.
>
> Donald,
>

<snip!>

>
>
> Thusfar I've scaled up the calculations provided in "Telescope Optics",
> calculated the corrector thickness, and made a half-scale drawing of the
> entire 'scope, NOT including the baffeling, which I am still analysing.
> I've also got a lead on where to buy the BK-7 or it's equivalent for the
> corrector, (thanks Peter Brooks!) and am considering having it slumped to
> save some time and effort.  I have the pyrex primary and assorted grinding
> material.  The primary, of course, will need to be cored.

Where are you getting the BK-7?  I've always wondered where you buy small
amounts of optical glass.  I've been thinking of doing a Mak-Newt.  Or a
Houghton.  Which is easier?  The meniscus has tighter tolerances, but the
Houghton has more surfaces.
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