Re: ATM schmidt camera

[andydtg@phoenix.net]

Re my 16" Baker-corrector, Michael Schmidt wrote:

>How much is the 18" diameter glass costing you? BK-7? From whom?

It's actually 19" dia 1/2" clear float plate, selected from
two that I bought from a local window glass supplier. I
tested them for strain & striae with polaroid & also did
a null test on the paraboloid with the glss in front of
it. The glass is not bad but will need to be ground/polished
flat on one side before doing the corrector profile on the other.
Cost (20 yrs ago) was <$100 including cutting. BTW the
original 48" Palomar Schmidt CP was plate glass also.

>And the focal plane reducer? How many lenses?

It's a conventional cemented crown/flint doublet, not
infinity corrected, I had it made by a commercial optical
house (total including glass & AR coatings was $400).

This project has been *long* term, the 16" newt/cass part
was done 20 yrs ago & I got sidetracked into the big Dob 
revolution & built a 24" & a couple of 32's...sky
around here not really dark enough for the Baker but
it *will* be in Cloudcroft. Now all I'll need is
a *cheap* 4" x 4" CCD camera..:)





Andy Saulietis / DTG Alt-Az-Fp Drive Systems
HDPE Worm Gears, Custom designs & Machine work
12617 Harriet Ln
Santa Fe, TX 77510 USA
409-925-8854 Voice/Fax
e-mail: andydtg@phoenix.net