Re: [APML] New Schmidt Camera image: Machholz onSaturday

[George Anderson <tillerman1@videotron.ca>]

KGKIRKLEY@aol.com wrote:

> George:
> Schmidt cameras have very fast focal ratios; ie. f1.5, f1.65, f2.0,
> f2.2 and their light cones are very steep, fat or whatever term
> applies. Any secondary would have to be very large to get the focal
> plane outside the tube and be accessible. The Tak Epsilon's do manage
> this but they are more like f3.3 and still have very large
> secondaries. I'm not saying large secondaries are a problem for
> imaging, because they are not, but a secondary for an 8 inch f1.5
> Scmidt would probably be 5 inches in diameter.
> 
> Kent Kirkley
> 

Hi Kent

My thoughts were to use a diagonal roughly the size of the schmidt
filmholder. The diagonal assembly would also have a plano convex field
flattener in the optical path just in front of the diagonal where the
image would be formed. Then outside of the schmidt case would be a
focuser with a relay lens (1:1) on the inside end of 2.4" focuser tube.
The idea of this lens is to focus the vitual image formed by the field
flattener inside the body of the schmidt camera onto the CCD. This would
allow the use of DSLR's with the schmidt.
The relay lens would be similar EP projection with a long FL eyepiece,
how much this would reduce the speed of the schmidt camera (possibly to
the extent where it would be no better than a 300mm camera lens) I can't
say.
Like I mentioned before, I suspect that Roland (and others) could shoot
this down in a heartbeat.

George Anderson
Montreal Canada

Clear skies and good health
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