How do I - Cleaning the Corrector Lens

I umpired 12 innings today and was tired when I got home. I set the
telescope up anyway because I wanted to see the crescent Venus before
it went away on me. It was low on the horizon and looked like it was
on fire with the roiling atmosphere. A quick tour of Saturn, Jupiter,
and the Terminator on the Moon followed. I noticed some lens flare
and, having taking pictures long enough, I immediately thought, "Dirty
Optics".

When I broke the telescope down I checked everything. All clean
except the corrector plate (Celestron C 91/4 SCT). It
was...well....filthy.

I've heard both pro and con to using compressed air. I've been using
a phtographic lens blower (squeeze type) but I've moved beyond that.

So, if I could get a quick opinion on:

1. Compressed Air (pro, con, do you use it).

2. Next step if Compressed Air won't do it.

I don't want drastic measures yet. This is just dust and should come
off without a great deal of trouble..

Clear, Dark Skies

Mark

Celestron and Meade both recommend on their websites a couple of things.
First, I hope when you said "break down" that you didn't remove the
corrector plate from the OT. If so, then I hope you marked the exact
position of corrector plate with regards to the OT, since both companies
make it a point to do this, the reason being that's how the corrector plate
is matched to the primary mirror. If this is not done, then you're not
going to have sharp views.

Whether you did this or not, the approve method of cleaning the corrector
plate is to use a solution of 60% distilled water, 40% Isopropyl alcohol
(not rubbing alcohol), usually more than 90% alcohol by volume, and a drop
or two of unscented, uncolored dish washing liquid. All can be had at most
local drug stores, along with a spray pump bottle to administer the liquid.
Don't overwet the lens. Use cotton balls to gently wipe the corrector plate
with the liquid, and let air dry after removing as much with a dry cotton
ball as possible.

Good Luck !
--
Sincerely,
--- Dave

----------------------------------------------------------------------
A man is a god in ruins.
--- Duke Ellington
----------------------------------------------------------------------

"Mark Smith" wrote in message
...
I umpired 12 innings today and was tired when I got home. I set the
telescope up anyway because I wanted to see the crescent Venus before
it went away on me. It was low on the horizon and looked like it was
on fire with the roiling atmosphere. A quick tour of Saturn, Jupiter,
and the Terminator on the Moon followed. I noticed some lens flare
and, having taking pictures long enough, I immediately thought, "Dirty
Optics".

When I broke the telescope down I checked everything. All clean
except the corrector plate (Celestron C 91/4 SCT). It
was...well....filthy.

I've heard both pro and con to using compressed air. I've been using
a phtographic lens blower (squeeze type) but I've moved beyond that.

So, if I could get a quick opinion on:

1. Compressed Air (pro, con, do you use it).

2. Next step if Compressed Air won't do it.

I don't want drastic measures yet. This is just dust and should come
off without a great deal of trouble..

Clear, Dark Skies

Mark

First, I hope when you said "break down" that you didn't remove the
corrector plate from the OT.


Nope. I'm not THAT gutsy. "Break Down" simply means "Put Awar for
the night" (Remove Star Diagonals, Eyepieces, cap openings, put in
cases, etc.).

OK. I thought you were braver than that. ^_^

Now, on with the alcohol solution !
--
Sincerely,
--- Dave

----------------------------------------------------------------------
A man is a god in ruins.
--- Duke Ellington
----------------------------------------------------------------------

"Mark Smith" wrote in message
news

First, I hope when you said "break down" that you didn't remove the
corrector plate from the OT.


Nope. I'm not THAT gutsy. "Break Down" simply means "Put Awar for
the night" (Remove Star Diagonals, Eyepieces, cap openings, put in
cases, etc.).

OK. I thought you were braver than that. ^_^

Now, on with the alcohol solution !
--
Sincerely,
--- Dave

----------------------------------------------------------------------
A man is a god in ruins.
--- Duke Ellington
----------------------------------------------------------------------

"Mark Smith" wrote in message
news

First, I hope when you said "break down" that you didn't remove the
corrector plate from the OT.


Nope. I'm not THAT gutsy. "Break Down" simply means "Put Awar for
the night" (Remove Star Diagonals, Eyepieces, cap openings, put in
cases, etc.).

First, I hope when you said "break down" that you didn't remove the
corrector plate from the OT.


Nope. I'm not THAT gutsy. "Break Down" simply means "Put Awar for
the night" (Remove Star Diagonals, Eyepieces, cap openings, put in
cases, etc.).

1. Compressed Air (pro, con, do you use it).

2. Next step if Compressed Air won't do it.


Hi:

Canned air works fine, just remember to hold the can upright at all times, and
keep the nozzle at least a foot from the corrector surface.

The next step depends on how dirty the corrector really is. Minor spots can be
taken care of with a Lenspen. Larger areas will require genuine cleaning. There
are several good ways to do this. One is to use lenstissues, lenstissue from a
camera store designed for lenses and not eyeglasses. I always use Kodak.

Moisten these with a little lens cleaning fluid (the recipe Meade has on their
website works well). Gently swap from the middle outward, rotating the tissue
to expose fresh surfaces and changing tissues frequently. Always apply fluid to
tissue, not corrector. Continue until clean, removing remaining fluid with more
tissues.

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

When cleaning my corrector, I use a solution of 1 pint distilled water
and 1 drop of ivory dish washing liquid. I'm sure that you'll find as
many recommended solutions out there as there are stars in the
heavens. Regardless of what you decide to use, clean your corrector
while the OTA is mounted. Point the corrector plate end down so
gravity works in your favor. Make sure none of that solution leaks
back into your OTA.

Michelle Stone
Custom Telescopes by Plettstone
http://www.plettstone.com

I was thinking about attaching an electrode from a Van de Graff
generator to my scope. Charge the entire assembly up to about 120,000
volts


HI Etok:

Or...you could just blow off a 10 megaton RV next to the corrector. _That'll_
get rid of them pesky dust-spots! :-)

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

It was low on the horizon and looked like it was
on fire with the roiling atmosphere.

Looked that way last night to me too in my Pronto.

A quick tour of Saturn, Jupiter,
and the Terminator on the Moon followed. I noticed some lens flare
and, having taking pictures long enough, I immediately thought, "Dirty
Optics".

When I broke the telescope down I checked everything. All clean
except the corrector plate (Celestron C 91/4 SCT). It
was...well....filthy.

1. Your scope is essentially brand new, it seems strange for it to be dirty so
soon.

2. The seeing was not so great last night. Also flare can come from other
sources, your own astigmatism, optics that are not cooled etc...

Jon