Re: ATM more on off-axis telescopes

["Andrew Schott" <aschott@cfl.rr.com>]

I've already thought of the body heat effect and figured that the tubes
would just have to be extended beyond the effect.  Ungangly as that may
seem, there should be no real problem with 2 or 3 foot extensions on smaller
tubes like this.  Fiberglass or PVC could be used as they are insulative and
should not couple the rising body heat into tube currents.  There's only two
months out of the year where that will be a problem here in Florida anyway!

I can't find any scope design in my scope history books that shows a true
off axis paraboloid, unobstructed design.  Herschel's design was one of more
expedience where he took spherical or whatever kind of speculum out under
the night sky, then like today's amateur star-testing for the first time, he
stood slightly off axis with his eyepiece and watched the stars go by.  I'm
sure it was more refined than that but I see no attempt in his early designs
to incorporate true off axis primaries.  Oh well, if I can't find any
historical reference, I'll just name the design after myself and call it the
Schottenspiegler:-)

Or maybe not....


----- Original Message -----
From: "Joe Mayenschein" <mayen1@mwt.net>
To: "Andrew Schott" <aschott@cfl.rr.com>
Cc: <atm@shore.net>
Sent: Sunday, December 30, 2001 10:55 AM
Subject: Re: ATM more on off-axis telescopes


>
>
> Andrew Schott wrote:
>
> > Many thanks to all who've responded to my brainstorming.  More arrive as
I
> > write this!
>
> {snip}
>
> >  Is it the Gregorian that has no secondary?
> > Herschiellian?  Which one actually uses the off axis paraboloid?
>
> it's the Herschiellian,, but wasn't that just a long sphere tilted
somewhat?
>
> >
> >
> > The light makes one bounce then it's in the eyepiece.
> > You stand between two 6" tubes that look back over your shoulders into
> > space.  The eyepieces are situated in such a way that the starlight
> > silhouette of your head barely grazes the primary's inside edge on
either
> > mirror.
>
> I see ONE BIG PROBLEM with this thought.  Your body heat is going to
royally
> mess up the incoming light.
> seeing will never be any good with you standing under the path of light.
>
> >
> >
>
> Joe
>
>