Would you be leaving this alone or would you of cleaned it long ago ...
Dirty mirror?
I´d give it a wash now!
It depends if the observing was affected…which it probably is. However, I've been surprised at how a "dirty" mirror still produces crisp images.
Personally I like my mirrors/ glass in general to "look clean" on visual inspection.
Personally I like my mirrors/ glass in general to "look clean" on visual inspection.
I wouldn't last another day without cleaning it 
and i would buy a cover 
The only reason to not clean it would be
otherwise I wouldn't see any disadvantage and I would clean it, just to be sure
and i would buy a cover The only reason to not clean it would be
- you compared with older pictures from a "clean" mirror and can be absolute certain that there is no loss of light (hard to evaluate)
- you don't have the time to carefully inform about the cleaning process (but there are lot's of tutorials on youtube/forums)
- you don't want to do the collimation again, which can be complicated for certain scopes
otherwise I wouldn't see any disadvantage and I would clean it, just to be sure
thnks for all your replys.
The scope is always covered when not in use.
I have recently installed a fan which helps with condensation so hopefully that will help in future.
Collimation.. the mirrors already un-installed and im comfortable with the procuedure for this scope.
My main reason for the question was if i was being overly anal in wanting to clean it.
I cant see how in its current state it wouldn't be degrading images?! but was curious what the consensus would in terms of if its current state met the threshold.
The scope is always covered when not in use.
I have recently installed a fan which helps with condensation so hopefully that will help in future.
Collimation.. the mirrors already un-installed and im comfortable with the procuedure for this scope.
My main reason for the question was if i was being overly anal in wanting to clean it.
I cant see how in its current state it wouldn't be degrading images?! but was curious what the consensus would in terms of if its current state met the threshold.
thnks for all your replys.
The scope is always covered when not in use.
I have recently installed a fan which helps with condensation so hopefully that will help in future.
Collimation.. the mirrors already un-installed and im comfortable with the procuedure for this scope.
My main reason for the question was if i was being overly anal in wanting to clean it.
I cant see how in its current state it wouldn't be degrading images?! but was curious what the consensus would in terms of if its current state met the threshold.
I have run one mirror for 10 years before deciding to clean it up. Reality is it takes an awful amount of dirt to visibly degrade the images and frankly I cannot be bothered to get everything down because of a bit of fluff. Shining light across a mirror surface might seem to highlight a lot of stuff deposited over there but one should resist the urge to make it look pristine as you may well run the risk of ruining it far more than any gain you might achieve.
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andrea tasselli:thnks for all your replys.
The scope is always covered when not in use.
I have recently installed a fan which helps with condensation so hopefully that will help in future.
Collimation.. the mirrors already un-installed and im comfortable with the procuedure for this scope.
My main reason for the question was if i was being overly anal in wanting to clean it.
I cant see how in its current state it wouldn't be degrading images?! but was curious what the consensus would in terms of if its current state met the threshold.
I have run one mirror for 10 years before deciding to clean it up. Reality is it takes an awful amount of dirt to visibly degrade the images and frankly I cannot be bothered to get everything down because of a bit of fluff. Shining light across a mirror surface might seem to highlight a lot of stuff deposited over there but one should resist the urge to make it look pristine as you may well run the risk of ruining it far more than any gain you might achieve.
Thanks for the benefit of your experience. I will take everyones comments onboard and decide.
Id say it looks like it needs a clean. I have twice cleaned my 14 inch mirror in place - with tube horizontal. Last time cos of several snail trails that had decided the OTA was a good home . just used a gentle spray of DI water from a 5 l garden sprayer followed by 50 % alcohol to help dry. I try to resist the temptation to touch the mirror with cotton etc - just a gentle spray. This is enough to get it reasonably clean. That said have not noticed a before and after difference, so wont repeat unless covered in volcanic ash or similar.
To me, it appears to need a cleaning. The dirt seems unusual. Like fibers.
A reason to not let dirt sit too long can depend on the type of dirt and type of mirror coatings. If just mineral dust or inert stuff, then it probably is not an issue. But if you accumulate a lot of haze because of forest fire smoke (like where I live), then leaving it may risk acids that can develop with moisture. One of the ways mirror surfaces are cleared of their coatings (Aluminized and overcoated mirrors) is to use acids. But most dichroic coated mirrors are pretty tough to such damage. I accumulated a good deal of smoke haze this summer, and then got fog forming on it. That concerned me. So I cleaned it. Most acids will not damage the glass, but can etch the coatings.
If you do get fogging, the moisture can cause the dirt to move about and line up in rows and patterns on the mirror. This can cause additional diffraction issues on bright stars. But I would not clean a mirror unless there is some issues seen in the images.
A reason to not let dirt sit too long can depend on the type of dirt and type of mirror coatings. If just mineral dust or inert stuff, then it probably is not an issue. But if you accumulate a lot of haze because of forest fire smoke (like where I live), then leaving it may risk acids that can develop with moisture. One of the ways mirror surfaces are cleared of their coatings (Aluminized and overcoated mirrors) is to use acids. But most dichroic coated mirrors are pretty tough to such damage. I accumulated a good deal of smoke haze this summer, and then got fog forming on it. That concerned me. So I cleaned it. Most acids will not damage the glass, but can etch the coatings.
If you do get fogging, the moisture can cause the dirt to move about and line up in rows and patterns on the mirror. This can cause additional diffraction issues on bright stars. But I would not clean a mirror unless there is some issues seen in the images.
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It was bothering me all so i gave it a gentle clean , mirror is back in its cell and mounted in the scope.Collimation checked and hasn't moved at all.
Since i installed a fan I have had no further issues with fogging so hopefully that will help prolong the periods between having to touch it again.
Since i installed a fan I have had no further issues with fogging so hopefully that will help prolong the periods between having to touch it again.