Re: OT: Re: [ATM] RE: Magnalium and add Null testing, here

["David Harbour" <scarab2@cox.net>]

Thanks, Richard,

For this link to the neat and different null test set ups for testing Cass.
systems. (And, I note, lenses). All of these tests are known well to me.

Nowhere, was the method I described, represented. The test I refer to is
where the Primary is set up, and the secondary is placed where IT IS
SUPPOSED TO GO in the finished optical system. The light source, is, of
course, at the Cassegrain focus, or it can be provided by a a collimator.
The light goes out from focus, travels between both mirrors (THE PRIMARY IS
ALREADY FINSIHED, AND PROVIDES, THEREFORE, PARALLEL LIGHT AS IF FROM A
STAR ) and then passes around the secondary, and strikes either a FLAT
MIRROR, or what is its equivelant for poor people, a pool of oil, or
Mercury, which is essentially "flat", and then goes backwards onto the
primary, which focuses (but the cone of light is intercepted from the
secondary and relayed to focus) onto the knife edge. I did not see this test
illustrated in the many rigs the link you sent provides me with.

Has everyone forgotten this test? Do we need to do any adding, subtracting,
calculus, to do this test when we are figuring?

No, no, no, no. Niether did Bernhard Schmidt, when he figured his first
corrector  plate (14" in diameter).

Someone tell me if this is just a fever dream of mine, or whether, by
thinking too much about nekked wimmin and flying wings, I have become mush
brained.

Dave

Math is overrated in telescope making.

Make a mistake in the placement, or power of a lens, or another mirror, such
as Perkin Elmer did, in the case of one of their famous set of telescope
optics, and you have egg on your face, bit time. Use a flat mirror, IT WILL
NOT LIE TO YOU.

http://www.atmsite.org/contrib/Harbour/Foucault.html


----- Original Message ----- 
From: "Richard F.L.R. Snashall" <rflrs@rcn.com>
To: "David Harbour" <scarab2@cox.net>
Sent: Saturday, May 07, 2005 6:20 AM
Subject: Re: OT: Re: [ATM] RE: Magnalium and add Null testing, here


> David Harbour wrote:
>
> >I think the methods are written up in the old Albert Ingalls/Scientific
> >American three volume atm-ing books. Where have all the greyheads gone?
> >
> >
> >
> And, for your late night enjoyment:
>
>     http://users.rcn.com/rflrs/sectest.htm
>


_______________________________________________
ATM mailing list http://www.atmlist.net/