Should I attempt to clean the main mirror of my scope?

[KingsAmis]

My mate lent me her smaller Dob for my nightshifts and while I’m fine collimating (it’s already not too bad it hasn’t been used much at all!) the mirror does have a few noticeable dust marks if that’s what I can call them.
 

In terms of how that affects my usage the first time using it seemed alright albeit I wasn’t using my lens and I didn’t know what to expect from a dob that small (Table-top 3 inch)

 

I’ve attached an image that shows some of the marks is it big enough of an issue that I need to take it out and clean the mirror? 

[Peter Drew]

Leave well alone.   🙂  Dust will have little impact on performance, the biggest dust spot is the secondary mirror and the scope works well enough with that.

[Moonshed]

Hi KingsAmis,

I asked the same question a couple of years ago because of the build up of dust and grime on my 35 year old 8” Celestron. I was surprised by the heated debate it started! Some members were adamant that the mirror should be left as it as while others said I should clean it.

I took the view that I clean all my other optics so why not the main mirror? I cleaned it, very carefully, following a clip on YouTube showing how it should be done. The difference in the before and after was remarkable and I am so glad I cleaned it. You mirror most likely will not be anything like as bad as mine and you will probably get away with cleaning just the secondary mirror, if it needs it.

Good luck either way and clear skies!

[Carbon Brush]

At risk of triggering another heated debate😲

If a mirror has toxic or reactive deposits, clean it.
That includes fungus, bird dropping, serious tree sap and pollen.

If a mirror is a couple or 3 years old and just has a few bits, leave it for another day, or year.

After 35 years it will pick up a lot of debri, whether harmful or not. Cleaning is warranted.

Mirrors can be sfely cleaned with the right technique and materials.
However, there is always a small risk of scratching or other damage.

If a mirror looks really grotty, I clean it.
If it is not really grotty but the scope is in pieces for other reasons, I clean it.
Otherwise leave alone.

Looking at the image provided, I think your scope is in the look again another day/year category.
You can have a lot of stuff on a mirror and still get good views.

HTH, David.

 

 

[Moonshed]

22 minutes ago, Carbon Brush said:

At risk of triggering another heated debate😲

If a mirror has toxic or reactive deposits, clean it.
That includes fungus, bird dropping, serious tree sap and pollen.

If a mirror is a couple or 3 years old and just has a few bits, leave it for another day, or year.

After 35 years it will pick up a lot of debri, whether harmful or not. Cleaning is warranted.

Mirrors can be sfely cleaned with the right technique and materials.
However, there is always a small risk of scratching or other damage.

If a mirror looks really grotty, I clean it.
If it is not really grotty but the scope is in pieces for other reasons, I clean it.
Otherwise leave alone.

Looking at the image provided, I think your scope is in the look again another day/year category.
You can have a lot of stuff on a mirror and still get good views.

HTH, David.

 

 

Sound advice!

[Shimrod]

On 25/02/2023 at 11:20, KingsAmis said:

My mate lent me her smaller Dob for my nightshifts and while I’m fine collimating (it’s already not too bad it hasn’t been used much at all!) the mirror does have a few noticeable dust marks if that’s what I can call them.
 

In terms of how that affects my usage the first time using it seemed alright albeit I wasn’t using my lens and I didn’t know what to expect from a dob that small (Table-top 3 inch)

 

I’ve attached an image that shows some of the marks is it big enough of an issue that I need to take it out and clean the mirror? 

 

In addition to the advice above to leave it alone, given that it is your friend's scope rather than your own, only clean it if you're prepared to replace the scope if it all goes horribly wrong.

Edited February 26, 2023 by Shimrod
corrected typo

[Moonshed]

3 hours ago, Shimrod said:

In addition to the advice above to leave it alone, given that it is your friend's scope rather than your own, only clean it if you're prepared to replace the scope if it all goes horribly wrong.

Or you can just say a big boy did it and he ran away.