Re: [ATM] computing Yolo

["Bob May" <rmay@nethere.com>]

That's the reason why there is a Tuthill Towers at Setllafane!
The guy really did a lot of interesting stuff back in the old
days.  Unfortunately, I got to only talk to him for a few minutes
one day while I was working on that building.
Bob May

rmay at nethere.com
http: slash /nav.to slash bobmay
http: slash /bobmay dot astronomy.net

----- Original Message -----
From: David Harbour <stainless_steel@suddenlink.net>
To: Bob May <rmay@nethere.com>; <atm@atmlist.net>
Sent: Monday, April 28, 2008 5:13 AM
Subject: Re: [ATM] computing Yolo


> Bob, all:
>
> The most elegant optical arrangement for a tilted component
telescope I ever
> saw was Roger Tuthill's unobstructed Maksutov Newtonian; all of
the curves
> were "regular"; (spherical, I think) all he had to do was tilt
both
> corrector and primary, and the instrument was done, and it
performed well,
> according to the article. I do not know how large it was; all
200 or so of
> my old Sky and Telescopes have gotten away from me. But if I
remember
> correctly (I believe I do) the diagonal was on (necessarily)
the side the
> optics were tilted to, and directing the image beam out on the
same side;
> however, I see no reason why a larger diagonal might be used,
and the beam
> directed across the tube to the other side.
>
> Roger is a genius, and seldom mentioned in this email forum.
Most everyone
> here must be youngish- me? I am "over the hill". Roger has made
more
> different kinds of optical systems for astronomy than most
people even know
> about. Roger Tuthill is a genius optician.
>
> Davey
>
>
> ----- Original Message -----
> From: "Bob May" <rmay@nethere.com>
> To: <atm@atmlist.net>
> Sent: Sunday, April 27, 2008 10:34 PM
> Subject: Re: [ATM] computing Yolo
>
>
> > Optical system generally don't scale up too well.  Shiefs in
> > particular don't like that at all.  Generally, the spot size
> > drops (the Airy disk) as the design is scaled up so what may
be
> > acceptable for a small scope where the Airy Disc is large
just
> > isn't so with a larger design wheere the Airy disc is smaller
and
> > the ability of the design to produce the aberrations is much
> > larger.  For example, it doesn't matter how big you build a
> > Newtonian, A F4 system will produce an image size of x before
the
> > coma gets large enough to be visible.
> > Schiefspieglers for example, get their performance because
they
> > have such long focal lengths compared to other designs that
it
> > just doesn't matter that much how bad the optical surface
really
> > is.  To get closer to a small value, there is often some
errors
> > put into the secondary and even the primary to bring the
focus to
> > a better point than the simple two spherical mirror setup.
Even
> > then, the aberrations are still there when the attempt is
done to
> > get the scope to a shorter focal length.
> > Bob May
> >
> > rmay at nethere.com
> > http: slash /nav.to slash bobmay
> > http: slash /bobmay dot astronomy.net
> >
> > ----- Original Message -----
> > From: Mircea Pteancu <mirceapte@yahoo.com>
> > To: <atm@atmlist.net>
> > Sent: Sunday, April 27, 2008 11:13 AM
> > Subject: [ATM] computing Yolo
> >
> >
> >> Please help me to understand what I'm doing wrong.I want to
> > build a small Yolo, in the aperture range of 3'' or 3,5''
.Carl
> > Anderson kindly done some calculations for me.Then I decided
to
> > treat myself with a tour into  the witchcraft of optical
> > design.Using ''winspot'' ,my KISS strategy was  this:I will
> > insert known designs and then I will use the ''scale''
function
> > of the software.I inserted the specs of Arthur Leonard's 12''
> > F/15 Yolo but the output of ''winspot'' was a F/25 system
with a
> > spot size bigger than my house compared to the Airy disk.I
will
> > try now the Knabe 3'' schiefspiegler ,recently discussed on
the
> > list.I'm not enough KISS or too much ? Thanks in
advance,Mircea
> >>
> >> ---------------------------------
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> > Mobile.  Try it now.
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> >>
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> >
>
>
>

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