ATM (no subject)

[GregJ888@aol.com]

Tony, I may be throwing gas on the fire but here are some things you might
want to try.

>The problem we are having is coming up with a 10" classical cass optical
>set.  I have proposed using a 10" standard mirror with a flat secondary at
>the cass focus. 

The flat secondary would not produce an image at the cassegrain focus unless
it is really large, and
 there is a really large hole in the primary.  It would however show the
position, scale and spacing.  If that is all you want to do pick up a lens
about the right size and send it in to be aluminized -- with the correct lens
this will
give you a cheap convex secondary.  Check into a Dall-Kirkham, pick the right
lens, refigure your 10 mirror and you'll have a reasonably good scope for the
purpose.

>In fact, I have a 10.1" f4.5 mirror which has a smooth figure but is about
>1/2 wave under corrected (by star testing).  

Seems to me the primarys in the Parks convertibles are about f/4.5, you may be
able to get one of their secondaries and get something that will work.  It
won't "match" your primary, but for your purposes may be "good enough."  A
full set of Parks optics would of course be much better.

We are all use to looking at real stars, which are the toughest of targets.
Looking at extended objects is much less critical, you may be able to get away
with much less than we can.  I used a pair of W.W.II era binoculars that
growing up, thought were quite good.  For spotting deer (tanks) birds and
stuff, they are fine, for astronomy -- they 
are awful, really awful.  


Good Luck

Greg Jones