Dust on mirror ?

[Dazraz]

Hi i got a 8" Dob and when i remove the tube cover i can see slight specs of dust on the mirror not loads but a few - The telescope is 4 weeks old - should i clean it or leave it ?

Regards Daren

[GazOC]

Leave it, it takes a lot of dust on a mirror to affect the views in any way.

[Doc]

I recently cleaned mine but it had watermarks all ove it caused by dew. If it's just dust I wouldn't wash it. Have you tried blowing the dust off, or a very fine camel hair brush.

[acey]

Leave well alone. Once the entire mirror is covered with enough dust to make it look noticeably dull then it's time to wash the mirror. I wouldn't worry about dew spots either.

In any case you shouldn't do anything to a new mirror as it can take a few months for the coating to harden fully through oxidation. Cleaning a new mirror is more likely to cause scratching.

[barkis]

Just as Gaz. said, it really has to be bad to affect capability.

When it does get to that state, then by all means remove it from the Tube, and immerse it in tepid water for a while. Doing this in the bath is good, especially if you have a shower head for rinsing of any soap suds. It is recommended that soap flakes are added to the wash water, allow to soak for a while, then rinse off. If any dirt remains, do it again. Don't use liquid detergent, some contain mild acid.

The mirror should be face up resing on a folded towel in the bottom of the bath. Just repeat the process until you are happy that it is clean. Rinse off again, then a final sluice with de Ionised water should complete thre job. Find a safe place to stand the mirror on It's edge, if it is clean, then all the water will run off it. Any persisteng globules of water can be carefully picked off with the corner of a tissue.

I never touch the mirrors surface with anything. The method should clean it without resorting to touching it with any cloth. The surface may well be hard, but it is surprising how easy it can be covered in very fine scratches. So don't be tempted.

As I always say, and I got this from a good source. "A dirty mirror will perform better than a badly cleaned one."

Ron.

[Lerxst]

Hah, you guys are all wrong. I always sandblast the mirrors on my scopes when they require cleaning. Too bad the sky's been without any stars lately, eh?