From: "mommoteandcoyote" 
To: "Richard Schwartz" 
Cc: 
Reply-To: "mommoteandcoyote" 


Richard,

Well... That is, of course, a wonderfully articulated synopsis of all of
the problems one must consider when one is deciding weather or not the
"Classical Schmidt Camera" is the instrument one should use for
the research one is contemplating.

However, in this specific case, in order to meet all the critical points
enumerated above.... An F/2.8 Schmidt Cassegrain Anastigmatic Flat Field
Camera should do the trick.  and your Hasselblad back, should work quite
nicely... Now as to the date and time function...  Well... I defer that to
the computer wizards out there.



Talk with you soon,
Coyot‚
----- Original Message -----
From: "Richard Schwartz" 
To: 
Sent: Wednesday, January 22, 2003 3:00 PM Subject: Re: Re:ATM An Old TMs Simple Query


>
> OK, I have a few schmidt questions...
>
> If I have a schmidt, I will end up with a lot of little round pieces of
> film.  What is a good way to cut the film to the requires shape and size?
> What is a good way to identify the films, index them, and store them?
What
> is a good way to take measurements off of them?  What is a good way to
warp
> the film to match the curved focal plane?   If a field flattener lens is
> used, what is a good way to remove distortion from the image, and to
correct
> measurements on the distorted image (assuming the exact center of the
image
> is not located).
>
> I think the science value is greatly enhanced when the images can be
located
> in time and space, and stored in a non-destructive way.   There is more to
> working with schmidts than just building the optics.
>
> What I really would like is (1) some kind of field flattener lens, and (2)
> something like a Hasselblad camera back that automatically records date,
> time, and approximate RA and Dec.
>
> . . . Richard
>
>
> ----- Original Message -----
> From: "Jerry Hudson" 
> To: 
> Sent: Wednesday, January 22, 2003 11:16 AM
> Subject: Re:ATM An Old TMs Simple Query
>
>
> >
> > To ol' Coyote -
> >
> > Your formula,
> > >  a*rho^2+b*rho^+b*rho^4...
> > giving the shape of the Schmidt plate, is
> > exactly opposite in sign to the wavefront
> > aberration describing an uncorrected spherical
> > mirror.  The glass introduces just enough extra
> > path length where it is thicker to compensate.
> >
> > A straightforward way to see how this all works
> > out, if you have the patience and either a
> > good calculator or BASIC, is to start
> > at the desired focal point of the sphere and
> > trace a ray, bouncing it off the sphere, and
> > taking it out to where it intersects a plane
> > positioned where you want the plate to go.
> > Figure out the path distance along that ray,
> > and subtract off the path distance for the
> > central ray.  THat's your "wavefront aberration."
> > If you plot this against radial distance of
> > the ray from the axis, you will get a 4th order
> > looking curve.
> >
> > Note that adding the rho^2 term simply re-focuses
> > the wavefront - you have this degree of freedom
> > to try to make the overall power of the plate
> > to be zero (avoiding all but a trace of color).
> >
> > I hope this helps.
> >
> > BTW, I'd enjoy a direct off-list exchange with
> > you about Schmidts - an interest of mine.  I've
> > only made one: a Wright-type Newtonian.  And, yes,
> > Edgar Everhart's articles were a great help to me!
> > He was a smart guy and a great glass-pusher!
> >
> > - Jerry Hudson
> >
> >
> >
>
>
>

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