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Black spots on my mirror

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#1 taki53

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Posted 06 October 2013 - 02:19 PM

:question: I recently noticed some black spots on the 10 inch mirror of my orion intell. scope. I'm not sure what it is. Should I have it removed? How can I do this? The scope is around 6 yrs. old. Thanks.

#2 aatt

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Posted 06 October 2013 - 08:02 PM

Remove the mirror cell and look if you can't tell from the front end and/or send a picture. They could be anything-pine sap, spider droppings. Insect bodies and feces should definitely be removed. Don't do anything hasty with the removal before having a plan on how to do it. There are many thoughts on mirror cleaning. Here's one

http://www.loptics.c...mirrorcare.html

#3 Locoman

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Posted 06 October 2013 - 09:38 PM

Mine had black spots and I took the mirror out and cleaned it. Turns out they were pin holes. Not good!

#4 SteveG

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Posted 07 October 2013 - 03:40 PM

A picture of these black spots would be helpful.

My mirror has a small spot were the coating is coming off. This, and many pinholes which are typical to most mirrors will not affect the performance to any noticeable degree.

#5 Starman1

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Posted 07 October 2013 - 04:52 PM

:question: I recently noticed some black spots on the 10 inch mirror of my Orion intell. scope. I'm not sure what it is. Should I have it removed? How can I do this? The scope is around 6 yrs. old. Thanks.

Step 1. Clean the mirror. If you've never cleaned the mirror, it's probably dirt, but it could be mold or oxidation.
http://www.youtube.c...h?v=9Y8xFnXFVGQ
Step 2. If the black spots didn't come off: recoat the optics: OMI or Galaxy, or Nova, or........
Or just let them be (after cleaning) and ignore them unless they grow. If they grow, then Step 2 for sure.

Mirror coatings last from one year to 20 depending on the conditions. If you live near an ocean and never clean your mirror, and store your telescope in a garage near solvents and paints, then possibly 1-2 years. If you store the scope indoors, don't use it a lot, are meticulous about cleaning the mirrors, and live nowhere near an ocean, then 10-20 years. It just depends.

#6 Binojunky

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Posted 08 October 2013 - 10:42 AM

Happened to me, coating had pin holes,DA.

#7 sqrlman

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Posted 09 October 2013 - 11:40 AM

When the coating has flaked off of the mirror those areas will look dark when looking at the face of the mirror.
Look through the back of the mirror while the mirror is aimed at the daytime sky or a lamp. If you see the light shining through the spots then the coating is missing in those areas. If you can't see light passing through the mirror then the dark spots are on the coating. It could be mold. Try cleaning the spots with 91% alcohol and a Q-tip.

Steve






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