[SJAAboard] Alternatives for Scope 28

[Rob Hawley (SJAA)]

Albert received the mirror back from Raycraft.  He jury-rigged it into the
scope.  Both Raycraft and Albert feel the mirror is still unusable. 

Here are excerpts from Raycraft
---------
"I'm sorry to have to tell you this, but the mirrors are still coming out
astigmatic.

In frustration, I called a friend of mine and asked for his opinion.  He
said, that if the back isn't ground flat it's going to give you troubles. I
told him about the slopes on the side. He said if they were ground flat,
then the mirror would be too thin.  Albert's mirror is a mystery. Maybe I
just lucked out on that one."
---------
Here are Albert's observations

"Very soft views, even with a 18mm Radian (80X). The Moon was fuzzy. I could
make out quite a few craters, but everything was soft. The unaluminized
mirror produced bright enough stars to do a star test. I estimate the
brightness corresponded to a 80mm refractor. The out of focus star images
bore no resemblance to diffraction rings. Stars came no where close to being
focused. Personally, I wouldn't consider aluminizing it."



Personally I consider this mirror to just be a slug of glass.  Albert
offered some high-risk suggestions of how we might be able to salvage it.
"Might" is the operative word.  I do not think that is worth the effort. I
reimbursed Albert for the cost of the refigure attempt.  I do not intend to
seek reimbursement from the club.

This leaves the question on how to proceed.  Albert provided these
suggestions ordered with my most favored first.

	1. Albert owns a Waite Research 12-1/2" f/5. His purchase price was
$850 ($1,300 new).  This is a very high quality mirror with about 1/15 wave
finish.  I can forward the full specs if anyone wants details. I assume this
is Pyrex, but Albert did not specifically say.

	2. Buy a Discovery 13" f/4.5 plate glass mirror for $749.  This
would be purchased directly from Discovery.  The specs say 1/4 wave optics,
but the 8" mirror I bought from them performed better than my 10" SCT.

	3. Take Albert's original offer and accept payment of $300 for
mirror 27. Albert would own the unbuilt scope. As I said last year the $300
price is realistic considering the quality of the mirror and the risk Albert
took.  Two similar mirrors (28 and one from George Felix) were total losses.
The mirror for the 14" was similar quality to 27.  It sold at the auction
for $200.

Part of this decision hinges on what are the club's needs.  I will address
that separately.

The woodwork for the scope was finished months ago.  Albert sent me these
pictures.
http://www.sjaa.net/loaners/scope28/

The scope has been done and in Albert's garage since January.  He has been
very patient, but wants the club to decide on a solution.  We need to be
prepared to select one of these alternatives on Saturday.

Rob Hawley