Did I damage my primary mirror??
Posted 26 April 2014 - 05:16 PM
Posted 26 April 2014 - 08:44 PM
Posted 02 May 2014 - 07:53 AM
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?
Posted 02 May 2014 - 08:26 AM
All I'm worried of is the longevity of the coating, so if the scope was under warranty I'd contact the vendor.
Posted 02 May 2014 - 04:41 PM
Good article with a lot of common sense.
For future reference, here's the best article I've found on mirror cleaning.
From Mike Lockwood:
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.
Posted 02 May 2014 - 11:30 PM
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.
Posted 03 May 2014 - 12:56 AM
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.