Aftermarket v's Factory supplied mirrors

Part of a response (by Jan Owen) to one of my earlier post (1.25' v's
2" accessories) was:

I have completely refurbished this scope over the years, adding top
quality mirror cells, exquisite mirrors (primary by Mike Spooner,
certified secondary by Antares).

Is it common for experienced astronomers to change out their perfectly
good "stock" mirrors with "after-market" mirrors strictly for higher
performance? Jan states "top quality... exquisite mirrors." Are
Spooner mirrors better than stock mirrors or just good substitutes when
replacements are necessary; as was her situation?

E.g. swapping a perfectly good Rochester Quadrajet carburetor with a
Holly 750, or, a stock Fender pick-up with a Texas special... Just
curious...

Errol
NOLA

Is it common for experienced astronomers to change out their perfectly
good "stock" mirrors with "after-market" mirrors strictly for higher
performance? Jan states "top quality... exquisite mirrors." Are
Spooner mirrors better than stock mirrors or just good substitutes when
replacements are necessary; as was her situation?

Almost certainly better, but would you know the difference? Maybe you
would, or would at some point in the future, and maybe you woudn't. Maybe
you don't care and just want something of high quality because you like high
quality stuff.

Anyway, tonight is looking pretty good (finally), and my sons and a couple
of friends and I are going to do a bit of observing and not worry about
equipment.

Dennis

Starboard wrote:
Part of a response (by Jan Owen) to one of my earlier post (1.25' v's
2" accessories) was:


I have completely refurbished this scope over the years, adding top
quality mirror cells, exquisite mirrors (primary by Mike Spooner,
certified secondary by Antares).


Is it common for experienced astronomers to change out their perfectly
good "stock" mirrors with "after-market" mirrors strictly for higher
performance?

It may depend on the quality of the rest of the scope. It might make
sense to upgrade the elements of an otherwise premium Dob, but likely
would not for a more basic scope (e.g, Orion XT-10).

Phil

"Starboard" wrote in message
oups.com...
Part of a response (by Jan Owen) to one of my earlier post (1.25' v's
2" accessories) was:

I have completely refurbished this scope over the years, adding top
quality mirror cells, exquisite mirrors (primary by Mike Spooner,
certified secondary by Antares).

Is it common for experienced astronomers to change out their perfectly
good "stock" mirrors with "after-market" mirrors strictly for higher
performance? Jan states "top quality... exquisite mirrors." Are
Spooner mirrors better than stock mirrors or just good substitutes when
replacements are necessary; as was her situation?

E.g. swapping a perfectly good Rochester Quadrajet carburetor with a
Holly 750, or, a stock Fender pick-up with a Texas special... Just
curious...

Errol
NOLA


Last time I checked, I was a male. And I haven't had any surgery today...

And replacement of the Meade mirror wasn't a NECESSITY. I replaced the
optics as the final step in making this scope capable of delivering visual
images as good as physically possible for a scope of this size.

So... two incorrect assumptions right up front...

For folks who know, use, and appreciate fine optics, there is a difference
between factory standard mirrors, and nearly perfect mirrors made by fine
craftsmen, though to the inexperienced observer, there may be no obvious
difference. It IS possible for a factory mirror to approach perfection.
But it doesn't happen all the time. The vast majority of mirrors coming
from the various OEM makers will do a very nice job for most of their
customers. Not an EXQUISITE job, but a very good job.

Some folks CAN tell the difference, and others probably never will...
Meade parabolic mirrors made in their Irvine facility, have generally been
quite good over the years, and my experience with Meade goes back over 25
years. There have been a (very) few that were not. The one I replaced
was quite good. I also have an Orion mirror for this scope that was made
by Discovery Telescopes back when they made Orion's scopes. IT is quite
good. Both of these mirrors are (still) about as good as you could hope
from semi-production line scope mirrors.

But there's another group of mirror makers whose specialty is directed
solely at making mirrors for folks who know how good mirrors CAN be, and
they make mirrors for those folks, who will gladly pay commensurate with
their quality. Carl Zambuto is one of those. So is Mike Spooner. There
are several others.

After you have been at this for awhile, you will understand.

--
Jan Owen

To reach me directly, remove the Z, if one appears in my e-mail address...
Latitude: 33.6
Longitude: -112.3

I've read that some folks grind their own mirrors. How successful are
they? I understanding that some folks are talented, but can a
commercial grade mirror be made without the use of "very expensive"
machinery? Have you looked through a scope with (a) home-made
mirror(s)? Or. is it something that one does for the pure sport of it?
It seems like quite and undertaking.

In fact, I thinking of putting it off a while.

Some might be inclined to make a fire by striking two stones together..
It's not terribly efficient in our age of advance pyrodynamics (oh,
the flair to create new words upon demand), but, still, there must be a
certain feeling of achievement in doing it..

JC

Errol
NOLA

I've read that some folks grind their own mirrors. How successful are
they? I understanding that some folks are talented, but can a
commercial grade mirror be made without the use of "very expensive"
machinery? Have you looked through a scope with (a) home-made
mirror(s)? Or. is it something that one does for the pure sport of it?
It seems like quite and undertaking.

Homemade mirrors can be awful, good, excellent, etc. We have three homemade
mirrors that
are very good to excellent, and one not so good (astigmatism). For us and
some of our firiends, making mirrors is an important part of amateur
astronomy. For others, mirror making is a one time thing. And for many
others, it is not of interest. However, I find the Foucault test simply
amazing and beautiful, and encourage everyone in our club to take a look at
least once.

In fact, I thinking of putting it off a while.


Why not buy a scope and start grinding a mirror - this way you will not have
to put off observing until your homemade scope is complete!

Dennis

Testy... (I swear, no pun intended)

Well, your choice word was "refurbished". According to my dictionary,
in short means "to clean, brighten, or renovate." Since you changed the
mirror, you didn't clean or brighten. You must have renovated. Now,
"renovate", according to same, means to restore by repair or..... Never
mind....

As for assuming "Jan" was a girls name, I apologize and stand
corrected... Please don't linger on it too long...

Errol
NOLA

Dennis,

Thanks. I do have a scope on order. I couldn't resist asking about the
homemade mirror. Definitely fascinating that one can actually make a
usable spherical or parabolic mirror.

I'm reading this link on foucault testing now.
http://www.jlc.net/~force5/Astro/ATM...ultTester.html

I hope to meet some astronomers in my area with similar interest.

Errol
NOLA

Starboard wrote:
Or. is it something that one does for the pure sport of it?

I had the sort-lived but very intriguing idea that I could teach myself
about optics well enough to slowly, carefully, grind my own lenses and
make a 6 or 7 inch semi-apochromatic refractor.

I started looking through a lens design book and it quickly began to
look nearly impossible to hand grind and match the lenses without having
a lot of expensive tools and testing devices. I only have the standard
assortment of Craftsman house tools.

If RC or TB or anyone who knows about this firsthand is reading this and
would comment...is it impossible or nearly so to hand grind an
apochromatic lens? What is the minimum of tools and testing equipment
needed?

I made a 6in reflector for Astronomy 101 in college and that was a lot
of fun. My professor was Dr. Walker Baker, who enjoyed teaching inmates
(prisoners) Astronomy in his spare time. He always commented that he
couldn't figure out exactly how they managed to cheat on his tests, but
a group of them always had the same answers. Then he showed graphs of
our performance compared to the inmates. To give you a better idea of
his sense of humor...he had a bumper sticker that read "Eschew
Obfuscation".

--
Clear Skies,
Paul Murphy

(remove gemini to email me)

"Starboard" wrote in message
ups.com...
Testy... (I swear, no pun intended)

Well, your choice word was "refurbished". According to my dictionary,
in short means "to clean, brighten, or renovate." Since you changed the
mirror, you didn't clean or brighten. You must have renovated. Now,
"renovate", according to same, means to restore by repair or..... Never
mind....

As for assuming "Jan" was a girls name, I apologize and stand
corrected... Please don't linger on it too long...

Errol
NOLA


I did use the term refurbish. And some of that was what I did... I
replaced, or upgraded, if you will, some of the lesser parts (focuser -
TWICE, spider and secondary holder, primary cell - but ended up moving
back to the original, and added a 9X60 finder in place of the original),
and then replaced some of the replacements, when even BETTER parts became
available (there have been many opportunities for this; this scope is 25
years old).

I bought the Orion mirror because I was hearing good things about their
mirrors, and it IS a good mirror, but not better than the original. And a
very good mirror was not in keeping with my objectives in upgrading &
customizing this scope. A top level mirror and an exceptional secondary
that would not degrade the image from the primary was what I was looking
for, and what I now have... And eyepieces that complement the rest.

It's a disease that strikes folks in this hobby... Some worse than
others. It's related to aperture fever, but somewhat different, too...
I've also been guilty of aperture fever, and have the scopes (and have had
even more) to prove it... The scope in question is my second smallest.

All these things come with due time in the hobby... And after enough
time, when your body simply can't deal with the size and weight anymore,
sanity returns, though slowly, and you again begin to be a little bit (a
LITTLE bit) more practical... And the quest for the best optics begins to
dim a little eventually, as your vision begins to deteriorate with age.
I'm just beginning to reach that threshold now...

Perhaps in your case, you are being more practical on the FRONT end... If
so, and you never get the FEVER, congratulations!

--
Jan Owen

To reach me directly, remove the Z, if one appears in my e-mail address...
Latitude: 33.6
Longitude: -112.3