Re: [ATM] Luri-Houghton prescriptions.

[Guy Brandenburg <gfbrandenburg@yahoo.com>]

Won't one lose a considerable amount of light by
having all those non-coated surfaces? At 4 surfaces,
losing 4% of the light on each one, that reduces the
transmission to 85%, roughly.

On our project, we hope to eventually get them coated,
by whom, I don't know. Calculating the thickensses
necessary for the various layers, and then getting
that right, in our vacuum chamber, sounds like not a
job for amateurs.

Guy

--- Aki Lötjönen <aki.lotjonen@phnet.fi> wrote:

> Hi Bob,
> 
> It will be a great telescope! My regards to him who
> ever is making that
> 12,5 " Lurie-Houghton Telescope. Wow! I really hope
> you have time and
> willing to make that big Lurie-Houghton Newtonian.
> I read others comments. I have nothing to add. I
> also think surface
> pairs is the right way to go. If there is an option
> to leave secondary
> spider away, why not to do so. Lens thicknesses from
> designed can vary a
> lot, no problems... Lurie-Houghton Newtonians are
> really forgiving!
> The lenses need not necessarily to be coated too.
> 
> Rgds,
> Aki Lötjönen
> 
> 
> > I'm planning on coring the lenses to 2" or maybe
> 2.5" and putting
> > the mount on them.  Why do a solid front glass and
> not use it to
> > support the secondary mirror.  I plan on the edge
> of the
> > secondary to be almost touching the rear lens. 
> The biggest fun
> > will be insuring that the center spacer is the
> correct depth for
> > the edge spacer.
> > Bob May
> > bobmay at nethere.com
> > http: slash /nav.to slash bobmay
> > http: slash /bobmay dot astronomy.net
> > Addresses have been munged up to keep spammers
> from bothering me.
> > replace the obvious words with the proper
> character.
> > Thank you for your understanding!
> > 
> > _______________________________________________
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> 
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Guy  Brandenburg
Washington, DC
My home page:
http://home.earthlink.net/~gfbranden/GFB_Home_Page.html
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