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How dirty is dirty enough to clean a mirror? Or the problem is something else...

beginner observing optics reflector moon planet
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#1 jfinizolas

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Posted 04 July 2020 - 08:38 AM

I have a 150mm (6") reflector that I have owned for about 6-7 years and never cleaned it for assuming that it was too complicated and the telescope would desintegrate the moment I touch the mirror or the screws holding it. 3 years ago my tripod broke and i stopped using the telescope after trying to fix the tripod many times and failing, yesterday I decided to try again and i finally got it fixed, then I decided to do some observing of the moon and Jupiter, but when I was looking through the eyepiece something was a bit off... I could barely distinguish Jupiter stripes and the moon craters looked a bit out of focus and not very defined. The 3 years that I left my telescope untouched I didn't properly store it and a bunch of residue and dust accumulated on the primary mirror, I cleaned the dust with a lens cleaning cloth but the mirror still looked smudgy , I searched on the internet about it and read that you only should clean your mirror when it is REALLY dirty, so now I am in doubt if the problem is the aparent mirror dirtyness or something else like collimation (which I never tried for the same fears of damaging the telescope) or if my 6 inch reflector simply isn't powerful enough to have the image quality necessary for distinguishing these features of the moon and jupiter and I didn't know it

#2 jfinizolas

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Posted 04 July 2020 - 08:44 AM

Some photos of the mirror

http://imgur.com/gallery/6ITyp0k

#3 tjschultz2011

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Posted 04 July 2020 - 09:11 AM

If you've never collimated, then that's likely the issue. I usually collimate before every outing. Once you get the hang of it, it's easy and quick enough to do. 



#4 MellonLake

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Posted 04 July 2020 - 09:14 AM

Do a star test, if there are missing portions in the diffraction rings it is very much time to clean the mirror.

I have cleaned my mirror twice in 2 years. I think it is pretty low risk if you read up on it first. I used the finger tip method. It worked well. I will say that less soap is better. The first time I did it I used too much soap Residual soap on the mirror will attract and stick dust to the mirror. Follow the instructions and do not exceed the soap amount and make sure the soap is mixed in well.

Edited by MellonLake, 04 July 2020 - 09:15 AM.


#5 jfinizolas

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Posted 04 July 2020 - 09:39 AM

Thanks for the replies, can you guys link me to any tutorial that you followed and had good results?

#6 Couder

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Posted 04 July 2020 - 09:40 AM

Mirror does not look that dirty to me



#7 sg6

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Posted 04 July 2020 - 09:52 AM

It needs a clan when it begins to bug you.

If it doesn't bother you then leave it, if it bothers you then clean it.

Just have a read on cleaning and approach it sensibly. Half the problem with cleaning it removeal, replacemnet and subsequent recollimation. Cleaning is in a way the small bit.



#8 JohnBear

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Posted 04 July 2020 - 10:37 AM

Welcome to CN! 

 

Owning a decent telescope implies either:

1) a willingness to learn and do basic maintenance on the OTA and mount (such as collimation and optical cleaning), 

2) hiring professionals to do the dirty maintenance work for you, OR

3) buying new telescopes whenever cleaning or adjustments are needed. 

 

Note that asking paid professionals if it needs adjustment or cleaning will ALWAYS get an affirmative response.  That is how they make money! 

 

Collimation is the really tricky one to learn, yet once you know how to do it it can literally be done in a few minutes.  However first collimation attempts by newbies often lead to disater and may take weeks or months to get right - even with multiple pages of guidance from CN forum members.

 

Seriously - get someone from you local astronomy club to show you how to do collimation if you have not done it before. It can be a rabbit hole of frustration if you have not done it before, but it is easy if someone shows you how to do it properly - in person.  Search the Beginners forum for the words "help" and "collimation" if you don't believe me.

 

Cleaning a mirror is relatively easy and safe the first time if you follow the online instructions. I use and recommend the OWL method on Youtube


Edited by JohnBear, 04 July 2020 - 10:49 AM.

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#9 jfinizolas

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Posted 04 July 2020 - 11:40 AM

That is a lot of useful info, thanks :) , I will follow your tips and do an update on the state of my telescope on this thread soon

#10 stargazer193857

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Posted 04 July 2020 - 12:25 PM

If your reflection looks hazy, so might your star image. If you just see several specks, don't worry about it.

I wonder if few mixed with dust is more corrosive than few alone, or helps precipitate the dew. I prefer to keep mine clean.

Edited by stargazer193857, 04 July 2020 - 02:32 PM.


#11 MellonLake

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Posted 04 July 2020 - 12:41 PM

Condensed water is actually quite acidic and on very clean surfaces will cause corrosion (even of mirror coatings). Basically, pure water absorbs CO2 from the atmosphere creating carbonic acid.

The nice thing about dust is it almost invariably has calcium in it. Calcium compounds are buffers that keep pH neutral.

The nice thing is that it is really hard to get a mirror clean enough that the condensed water on the mirror becomes acidic.
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#12 makeitso

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Posted 04 July 2020 - 01:15 PM

What do you mean by condensed water? Distilled water maybe the same thing?

 

Thanks, Jack



#13 airbleeder

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Posted 04 July 2020 - 01:52 PM

   Collimation is not too difficult to learn. There may be a bit of a learning curve to become very good at it, but it's not so difficult that it should take weeks or months to improve your views.

   You might read up on the various tools, which do what, how much they cost. Order one and learn to use it.

   I learned with a combo tool which is cheap plus you can use it to do all adjustments. There is a learning curve, but once you get the hang of it and what you are looking at, you're on your way to not only better views but also confidence your telescope is performing up to it's potential. The Lightpipe is a very good combo tool.


Edited by airbleeder, 04 July 2020 - 01:54 PM.


#14 MellonLake

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Posted 04 July 2020 - 02:51 PM

Distilled water still has enough dissolved calcium not to be acidic. Deionized laboratory grade water or water condensed from the air onto very clean surfaces is acidic. I would not worry about any distilled water you would buy at a hardware or drug store as being acidic.

#15 MellonLake

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Posted 04 July 2020 - 02:52 PM

The condensed water is water that forms on the mirror when you take it from cold to hot.
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#16 N3p

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Posted 04 July 2020 - 03:28 PM

I clean the mirror approximately once per year preventing any buildups, usually, I clean it after pollination of the trees, that's about the only moment when particles really get inside the tube.  If there was no event or cause for concern, once per year might not even be necessary.

 

But doing once per year or so will prevent any nasty build ups, I prefer that then fighting against a very old film which needs to apply more pressure on the surface and which could contain abrasive dust. I cleaned a very old film once and clearly for me this was abuse..

 

Chinese mirrors are resistant, they have a protective coating on them.. putting it in distilled water with a bit of neutral dish soap should not cause any damage to it at all like the previous Owl technique.



#17 makeitso

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Posted 04 July 2020 - 05:27 PM

The condensed water is water that forms on the mirror when you take it from cold to hot.

I was thinking like condensed milk, just add water, lol. Condensation didn’t enter my mind, why I had to ask.

 

Jack


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#18 stargazer32864

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Posted 04 July 2020 - 05:53 PM

After my first experience cleaning my mirror for the first time since buying it new 10 years ago. I decided to send my next one off to be cleaned and re-coated after so many years. I will let everyone know after I get this new one in. The first scope, I made a lot of mistakes on and I'm surprised it didn't grow legs and walk out. I tried GENTLY cleaning it with soap, water, and cotton balls. Using a new one for each swipe from center to edge. It never did come clean. I even let it soak for three hours. It was like someone glued dust to the mirror. When I got done with it I had ruined the mirror and just put it back together and gave it away. So I will just let someone else mess with it and hope they know what their doing.

 

~Robin



#19 airbleeder

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Posted 04 July 2020 - 06:01 PM

    I haven't sleeked a mirror since I stopped using cotton balls and started using my finger tips to clean mine.


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