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Cleaning primary mirror

Sharpstar SCA260 Reflectors Cleaning
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Tomas Kocanda avatar
Tomas Kocanda avatar
Hi friends
my SCA260 primary mirror is full of gray dots as rest of dried dew on humid nights. 
What do you suggest for clearing? Possible to do it without removing rear end and removing mirror from the scope?
John Hayes avatar
John Hayes avatar
I can tell you how to clean it but not without removing the mirror from the scope.  It just too small to get your hands in there to do the job right.  Unless the mirror is really dirty, I DO NOT recommend cleaning it.  It takes a LOT of grime to seriously impact the imaging performance of the scope.

Get a new, clean spray bottle, a jug of distilled water, a box of Kleenex brand pure facial tissue (do NOT get anything with lotion) and a bottle of 99% (or better) pure isopropyl alcohol available from the grocery store or a pharmacy.  Remove the rear end of the scope so that you can easily get to the mirror surface.  Mix the alcohol with water about 1:7 in the spay bottle and shake it up.  Then spray the surface of the mirror and use the tissue to blot it dry.  DO NOT wipe.  Continue to spray and blot until the no more dirt is being removed.  Then soak the mirror and gently begin wiping the mirror to remove any film.  As the mirror becomes cleaner, you can wipe more aggressively.   Use a VERY bright flashlight to lighly spray and polish the mirror until it looks like new–with no apparent film anywhere.  When you are done, the mirror should look like new and you can reassemble the scope and get it realigned.

John
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Kevin Wigell avatar
Kevin Wigell avatar
John… Removing the mirror. I assume you do so by removing the 6 socket-head bolts on the outer perimeter of the back of the scope with a 3 mm hex wrench? Correct? I have been stressing about which bolts to loosen.

With those 6 socket-head bolts removed, you then just lift on the handles and the mirror will come straight out?

Kevin
John Hayes avatar
John Hayes avatar
Unfortunately, I don’t know your scope so you'll have to figure that out on your own.

John
Ashraf AbuSara avatar
Ashraf AbuSara avatar
I would reach out to Sharpstar for instructions before attempting this. Like John said it would take an awful lot of dirt to cause a problem. 

Most important thing is to never touch that corrector lens group.
surfinash avatar
surfinash avatar
Dry dust is not an issue. You can use the swifter to simply clean that off the surface with that electromagnetic pull. The handle/rod will allow you to reach the mirror. The dew spots (with dust settled over time) are tough to remove with dry wiping. 

I have successfully cleaned the primary using the swifter duster handle and a microfiber cloth. Did not need to remove the primary, and the rod helped me reach the mirror from the front. Here is the link to the duster handle - LINK

What I did was to wrap the microfiber cloth in the tongues / forks, and just use the painters tape at the bottom to hold that as a role. Left some room on the top (about a couple of inches) to create the "mop". You can then use your choice of cleaning solution (Pec-12, or the lens cleaning wipes, soap solution, etc). What I'd suggest to use one piece of cloth per wipe (go CW or CCW once, and use a new piece of cloth for the second round). I use the costco lens wipes. They are very wet, and I soak/wet the microfiber cloth "mop" by wrapping the lens wipe on the cloth and let the moisture soak-into the cloth. Then I use this semi-wet "mop" to clean the mirror.

Disclaimer - this is my approach, and if you decide to follow it, please do it at your own risk.
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Alex Nicholas avatar
Alex Nicholas avatar
A process as stated above by surfinash is completely fine, until it isn't… Unless you really don't care about scratches or chips in your primary, don't do that… 

Anything that can fall, will fall eventually… and if you go hanging a duster into your OTA to clean the primary, eventually, something is going to go wrong.. a drop, or something will come apart etc.. Something will eventually go wrong. It might not be the first time, or in the first 10 times… but it will..

As John said, figure out how to remove the rear cell of the telescope and clean the mirror out of the tube, then reassemble it. 
I've done this with a 5 and 8" newt, a 10 and 12.5" RC and a 9" dk… Each of these scopes had a very different process to get the primary out, however the process to clean the mirrors was exactly as John described..
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surfinash avatar
surfinash avatar
Alex Nicholas:
Anything that can fall, will fall eventually... and if you go hanging a duster into your OTA to clean the primary, eventually, something is going to go wrong.. a drop, or something will come apart etc.. Something will eventually go wrong. It might not be the first time, or in the first 10 times... but it will..


Not to split hair on this - but I provided the disclaimer in my post. Because something worked for me does not mean it would work for someone else - and I totally respect that. I agree with Alex on Murphy's Law. Probability of an unpredicted event happening is 50% to start with (before the event) - and it is universal. By that logic - the same probability applies toward "accidentally dropping/slipping the primary out of hands on the floor while removing it"... So, it all depends on the individual risk tolerance.