Re: ATM Off axis Parabolas

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

I've thought about that too.  I'm kind of hoping that the combination of 5"
f/10 or f/11 would decrease the divergence to something manageable.  I could
probably use a little wider divergent system than most people as I'm
practiced in merging stereo pairs up to 8"X10" enlargements.  It's not
comfortable and not something that would be comfortable to use for any
length of time.  Most people have great difficulty diverging their eye's aim
points even a little so I wouldn't be able to share a scope so designed.  I
was thinking that a small wedge of glass could be used in each eyepiece
mount to bring the fields into a more parallel configuration.  No
magnification, just a wedge.  These have been used in stereo viewers for
years to fudge the eye's inability to diverge and make it possible to fuse
stereo images larger than 2-1/4"X2-1/4".   Long before I would begin
fabrication of the primaries, I would set up some test apparatus to see if I
could indeed comfortably view through two eyepieces set at the angles
necessary.  It might work better than you think.

----- Original Message -----
From: "Ken Hunter" <kb7h@onemain.com>
To: "Jeff Morgan" <jeffmorgan@mindspring.com>; <atm@shore.net>
Sent: Sunday, December 30, 2001 12:42 PM
Subject: Re: ATM Off axis Parabolas


>
> For the system being described, NO SECONDARIES...
>
> It wont work if youare going to  make binoculars. Your head will be in
> the way of the optical path. If you separate the mirrors wide enough
> to get the light past your head you will need to put secondary optics
> into the path to make the two optical paths parallel. You will be
> unable to diverge your eyes enough to make the images converge into
> one if there are no secondary mirrors.
>
> Ken Hunter
>
> ----- Original Message -----
> From: "Jeff Morgan" <jeffmorgan@mindspring.com>
> To: <atm@shore.net>
> Sent: Sunday, December 30, 2001 12:24 PM
> Subject: Re: ATM Off axis Parabolas
>
>
> >
> > I was browsing old issues of S&T and back in the '60s or '70s there
> was an
> > ATM article about a folded Herschellian, something like a 5" f/12.
> What the
> > author did to fix the astigmatism was have his optometrist generate
> a toric
> > lens for placement just ahead of the focuser.
> >
> > Has anyone pursued this type of solution? If a prototype worked,
> certainly a
> > precision toric lens could be substituted for the LensCrafter
> special. Of
> > course to go to all of this trouble one would want a larger
> aperture,
> > otherwise you could just get a refractor. What other abberations
> would have
> > to be dealt with in a scaled up system, say for a 10" f/9 system
> with a
> > primary tilt of 6 degrees?
> >
> > As an alternative to the toric lens, would warping the primary
> paraboloid
> > offer any promise?
> >
> > > Date: Sat, 29 Dec 2001 22:06:45 -0700
> > > From: "Bill T." <twentiethwave@hotmail.com>
> > > Subject: Re: ATM Off axis Parabolas
> > >
> > > There's an excellent article by Gary Frishkorn on making an
> off-axis
> > > Herschelian mirror.  It's in issue 13 of the Amateur Telescope
> Making
> > > Journal, the one with the Mirror-0-Matic on the cover.  Basically,
> he
> > > attaches an asymmetric arrangement of lever arms to the back of
> the mirror,
> > > then hangs water bottles from the levers, then polishes the
> stressed mirror.
> > > The article is long and detailed with excellent illustrations.
> > >
> > > Bill T.
> >
> >
>
>
>