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Did I damage my primary mirror??

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#26 sickfish

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Posted 26 April 2014 - 05:16 PM

Thanks Don I will pull the mirror off and rinse it. I will try to take a picture before. Also it gives me a chance to try this. I will start a new thread. I am sorry if i hijacked this one. Once again Thanks

#27 staticclover

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Posted 26 April 2014 - 08:44 PM

No problem at all, as long as it brings Mr Pensack to the conversation!

#28 staticclover

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Posted 02 May 2014 - 07:53 AM

I think I am going to let the mirror ride for now. The views look good to me, the stars are pinpoints and the planets look good on good nights. I am new to this and haven't looked through many scopes to know how good it should look. I am going to take another look at it when it's ready for cleaning again.

Can anyone recommend a good place to have the mirror recoated if I go that route?

Know any good articles or videos on how to do a star test properly?

#29 sixela

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Posted 02 May 2014 - 08:26 AM

It's not going to affect the star test. It might make your sky background a tad lighter, but even that is not something I suspect will happen.

All I'm worried of is the longevity of the coating, so if the scope was under warranty I'd contact the vendor.

#30 craigLambert55

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Posted 02 May 2014 - 09:03 AM

For future reference, here's the best article I've found on mirror cleaning.

From Mike Lockwood:

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

#31 Starman1

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Posted 02 May 2014 - 04:41 PM

For future reference, here's the best article I've found on mirror cleaning.

From Mike Lockwood:

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

Good article with a lot of common sense.
See also: http://www.youtube.c...h?v=9Y8xFnXFVGQ
for a video on a gentle, easy, technique for cleaning a mirror.
And see: http://adsabs.harvar...PASP..109..303M
for an article on why and how often you should clean a mirror.

#32 Glen A W

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Posted 02 May 2014 - 11:30 PM

I don't think the mirror looks at all bad. With a high power flashlight, I'd imagine all of mine would look that bad. I've seen much worse in action in large observatories. I have never seen a mirror that looked at all perfect with a flashlight, and many look awful.

I am surprised to hear all this talk of washing mirrors. Though there is nothing to be afraid of if you clean one right, the idea that your reflectance can decrease by 20 percent in a year must only be true if you are living in a very bad area. I've found many scopes can go for years without cleaning.

PS- My Celestron C-10N looked just the same when last I cleaned it, in the Fall. I have not detected any problems. I have a 12" Orion Dob which looks worse because the previous owner let his dog sit it in, and I had to go nuts when cleaning - really not good to do. It is still a good scope to use, and gives great images.

I try not to be too picky, because I haven't found this all to matter much, though for the outright best on Jupiter I have seen some real difference in a really well polished and coated mirror, I must admit.

Glen

#33 Starman1

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Posted 03 May 2014 - 12:56 AM

Glen,
A friend who coats mirrors for a living cleans all the mirrors sent to him, and he has found an average of 25% increase in reflectivity, on each mirror sent to him for recoating, just by cleaning.
Reflectivity decreases from grime on the mirror is real.
But, remember than a 40% loss in reflectivity only loses a magnitude. Unless you regularly look at targets near the scope's limit, that may not be that noticeable to the average observer.






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