Astronomers - How to clean a mirror on a telescope?

bernse

Diamond Member
Aug 29, 2000
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I've got a 10" dobsonian that I noticed needs a cleaning of the secondary mirror quite badly. It appears to me that condensation has evaporated on it many times and you can see the "mineral" buildup of the water on it pretty badly now.. and it defintely is effecting the quality of the image.

I know ideally you should never have to clean a mirror on a scope in the first place, but how should a person clean a mirror on a telescope if you have to?
 

Spacehead

Lifer
Jun 2, 2002
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9,858
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Be careful. A scratched mirror is worse than a dirty one.
I haven't cleaned mine yet but i'm sure they could use a good cleaning.

One of the guys in our astronomy club has a recipe he uses but i'm not exactly sure what it is. I know you should use surgical grade cotton swabs, distilled water, isopropyl alcohol & maybe some detergent. Just not sure of the amounts. Careful what kind if detergent you use, if any at all.

I'm sure there are some how-to's on the web. Look around.
 

arcas

Platinum Member
Apr 10, 2001
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Google for Doc G's cleaning solution recipe. It's a homemade cleaning solution that works very well for cleaning the corrector plates of SCTs. It -might- work well for a mirror, too, but you might want to send Doc G an email since you'll be applying directly to an aluminized surface.

You might also search/ask in the forums over at astromart.com or even the various telescope forums hosted by yahoo.
 

Eeezee

Diamond Member
Jul 23, 2005
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Short answer, you don't clean your mirrors. You should be taking better care of them

Long answer, clean them VERY CAREFULLY ;-) If it's a secondary mirror, it's probably going to be incredibly fragile. Too much pressure applied and it's ruined (I don't even mean cracking it, either).
 

bernse

Diamond Member
Aug 29, 2000
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Originally posted by: Eeezee
Short answer, you don't clean your mirrors. You should be taking better care of them

Long answer, clean them VERY CAREFULLY ;-) If it's a secondary mirror, it's probably going to be incredibly fragile. Too much pressure applied and it's ruined (I don't even mean cracking it, either).
How can I take better care of them? Telescope is outside in -30 weather. When it is brought inside, condensation forms.

Can you think of a way to avoid it?