Cleaning the primary mirror.

[NIGHTBOY]

I've got a couple of black dots on my primary mirror, whats the best way to clean it? Also, how do you reach down an 8''dob??  

[Charic]

NIGHTBOY.......... a few dots wont hurt, but the temptation to clean will be irresistable. Some say a puffer brush to remove dust, You cant effectively reach down that far without doing something wrong inside? The mirror can be taken out to clean. An easy enough task, but have caution. The Mirror itself, minus the clamps can be washed, B.P cotton wool dragged lightly over the mirror to loosen anything that did not come off in the wash, rinse with distilled water only, to prevent water staining, followed by re-assembly, collimation. It will be some time before dust on the mirror will really affect your viewing. There are several `youTube` videos covering the issue.

[mdstuart]

Unless your mirror is very dirty then the best advice is to leave it..

If you want to try, remove the mirror from the base and then put it under a running tap...once covered in water add a few drops of washing up liquid and swish cotton wool over the mirror but barely touching the surface then take out rinse with distilled water and dry gently with a hair dryer...

Mark

[alan potts]

If that is all that is wrong with it I would leave oit alone. A bit of dust and a few bits and bobs on a mirror will have no noticable affect what so ever. I have had my main scope for 6 years now and I have only cleaned the front collector plate once, even then it still looked the same.

Alan

[LukeSkywatcher]

A few specs  of dirt/dust wont mess with the view. No need to clean. Maybe try a rocket blower to remove them.

[swamp thing]

Yep! As has been said, Leave it alone.

[damnut]

Hi There,

The thing to remember is if you think of cleaning your mirrors follow these steps :---

1. Make cup of tea.
2. Think about cleaning mirror. If Thirsty goto step 1
3. Goto step 2.

 

[ScottS]

Not done this myself yet, but from what I have seen, the potential to cause irreversible damage to your primary vastly outweighs the benefits. So I won't be cleaning mine until it really needs it.

[Zakalwe]

This question comes up all the time.

The general advice is not to clean it for a couple of reasons:

1- It will make no difference...a mirror has to be absolutely filthy to make any difference to the view (and by filthy, I mean filthy)

2- It easy to cause damage, and as there is no gain to be had, it simply is not worth the risk and effort.

Have a look at this:

http://stargazerslounge.com/topic/164263-primary-mirror-cleaning/?p=1663363

[Tonys]

I've cleaned the mirrors in my 200P Dob and Tal 2 having mistakenly thought they were really dirty and it made no discernible difference whatsoever, at least not to my eyes. My error in both cases was to accidentally shine my head torch onto the mirrors during observing sessions, which magnifies every tiny speck of dust. Having said that, there is satisfaction in knowing I can strip down my scopes, put them back together again and find they still work. The Youtube video by OpticWaveLabs gave me the confidence I needed.

[NIGHTBOY]

So you wouldn't class this as 'too dirty' then??? God knows how its got in there as the dust cover is always on.... If I shine a torch down the scope you can see dust floating around inside. I suppose being stored upright doesn't help as it settles on the mirror.

[damnut]

Thats only just qualifies as dusty. Good advice above, use a good quality puffer brush to shift the loose particles. It'll be cleaner, you'll feel better, but you won't notice at the eyepiece