mold versus coating breakdown on SC8 primary mirror

I have recently inspected the optics of my Super C8+ which has been
long neglected (years), sitting in its footlocker in my garage. After
removing the corrector lens and getting a better view of the primary
mirror, I can see what looks like small patches of mold, each
approximately 1/8 to 1/4" inch in diameter, scattered over the mirror
surface. I lightly touched one patch with a q-tip wetted with
distilled water. The "mold" was wiped away, leaving a slight
discoloration of the mirror beneath. The scope is about 20 years old
and has been subject to seasonal hot and cold while sitting in the
garage.

It seems that I have a serious problem, and I'm unsure what to do at
this point.

Should I take the primary mirror out of the tube and attempt to clean
it? If so, how is the mirror removed, and will it be a bitch to
reinstall and properly align it?

OR, is cleaning it even a viable option? IS the mirror finish
compromised and do I need to have the mirror recoated?

And if so, what's involved in that and how much would it cost to have
it repaired versus buying a new one.

Any help would be appreciated, as I am clearly out of my league but
would like to get the scope restored to top working condition.

Lee

In June I took my C5+ to Celestron due to considerable haziness in the
optics. They originally planned the clean and recollimate it.

But the optics had been stained. The had to recoat them and
recollimate, etc. Cost was $175, and well worth it to me: A great
travel scope!

Apparently my stains (on an 8 yr old scope) were due to a leaking roof a
few years ago near where I had the scope stored in a C5+ soft case. I
did not check the scope at the time, but I suspect that was the cause.

Phil

Lee Rouse wrote:
I have recently inspected the optics of my Super C8+ which has been
long neglected (years), sitting in its footlocker in my garage. After
removing the corrector lens and getting a better view of the primary
mirror, I can see what looks like small patches of mold, each
approximately 1/8 to 1/4" inch in diameter, scattered over the mirror
surface. I lightly touched one patch with a q-tip wetted with
distilled water. The "mold" was wiped away, leaving a slight
discoloration of the mirror beneath. The scope is about 20 years old
and has been subject to seasonal hot and cold while sitting in the
garage.

It seems that I have a serious problem, and I'm unsure what to do at
this point.

Should I take the primary mirror out of the tube and attempt to clean
it? If so, how is the mirror removed, and will it be a bitch to
reinstall and properly align it?

OR, is cleaning it even a viable option? IS the mirror finish
compromised and do I need to have the mirror recoated?

And if so, what's involved in that and how much would it cost to have
it repaired versus buying a new one.

Any help would be appreciated, as I am clearly out of my league but
would like to get the scope restored to top working condition.

Lee

OK. I've read a lot about it, but I've never encountered it. What causes
mold on eyepieces/optics and how do you prevent it?

Peace,
Jon


"Phil Wheeler" wrote in message
...
In June I took my C5+ to Celestron due to considerable haziness in the
optics. They originally planned the clean and recollimate it.

But the optics had been stained. The had to recoat them and
recollimate, etc. Cost was $175, and well worth it to me: A great
travel scope!

Apparently my stains (on an 8 yr old scope) were due to a leaking roof a
few years ago near where I had the scope stored in a C5+ soft case. I
did not check the scope at the time, but I suspect that was the cause.

Phil

Lee Rouse wrote:
I have recently inspected the optics of my Super C8+ which has been
long neglected (years), sitting in its footlocker in my garage. After
removing the corrector lens and getting a better view of the primary
mirror, I can see what looks like small patches of mold, each
approximately 1/8 to 1/4" inch in diameter, scattered over the mirror
surface. I lightly touched one patch with a q-tip wetted with
distilled water. The "mold" was wiped away, leaving a slight
discoloration of the mirror beneath. The scope is about 20 years old
and has been subject to seasonal hot and cold while sitting in the
garage.

It seems that I have a serious problem, and I'm unsure what to do at
this point.

Should I take the primary mirror out of the tube and attempt to clean
it? If so, how is the mirror removed, and will it be a bitch to
reinstall and properly align it?

OR, is cleaning it even a viable option? IS the mirror finish
compromised and do I need to have the mirror recoated?

And if so, what's involved in that and how much would it cost to have
it repaired versus buying a new one.

Any help would be appreciated, as I am clearly out of my league but
would like to get the scope restored to top working condition.

Lee

OR, is cleaning it even a viable option? IS the mirror finish
compromised and do I need to have the mirror recoated?

Hi:

In these case, usually not. About the best you can do is hope to stop the
growth of the fungus. If the primary isn't just _covered_ with spots, your
views should be relatively unaffected. As to whether you should try to get it
recoated, that depends. How good are the optics? Starbright? In most cases the
correct answer is "new OTA".

Peace,
Rod Mollise
Author of _Choosing and Using a Schmidt Cassegrain Telescope_
Like SCTs and MCTs?
Check-out sct-user, the mailing list for CAT fanciers!
Goto http://members.aol.com/RMOLLISE/index.html

The coatings are starbright. Forgive my ignorance, but what is meant
by "new OTA"?

Regarding cleaning the mirror, there are enough moldy patches on it
that it would seem easier to remove the mirror from the tube for
cleaning. How is the mirror removed, and can I anticipate realignment
problems when I reinstall it?

Lee



(Rod Mollise) wrote in message
Hi:

In these case, usually not. About the best you can do is hope to stop the
growth of the fungus. If the primary isn't just _covered_ with spots, your
views should be relatively unaffected. As to whether you should try to get it
recoated, that depends. How good are the optics? Starbright? In most cases the
correct answer is "new OTA".

Peace,
Rod Mollise
Author of _Choosing and Using a Schmidt Cassegrain Telescope_
Like SCTs and MCTs?
Check-out sct-user, the mailing list for CAT fanciers!
Goto http://members.aol.com/RMOLLISE/index.html

Regarding cleaning the mirror, there are enough moldy patches on it
that it would seem easier to remove the mirror from the tube for
cleaning. How is the mirror removed, and can I anticipate realignment
problems when I reinstall it?

Hi:

Removing mirror and mount is fairly easy. It requires disassembly of the focus
mechanism and removal of a snap ring. See
http://ngc1514.com/Celestron/disassem.htm for full instructions. Be sure to
put the corrector back on in exactly the same radial orientation as before.


OTA= Optical Tube Assembly. C8 OTAs are fairly plentiful on Astromart, and you
might be able to get one cheap enough to encourage you to go that route.

Peace,
Rod Mollise
Author of _Choosing and Using a Schmidt Cassegrain Telescope_
Like SCTs and MCTs?
Check-out sct-user, the mailing list for CAT fanciers!
Goto http://members.aol.com/RMOLLISE/index.html