Clean your dirty mirror

Tony Gondola · Mar 30, 2026, 02:56 PM

Interesting result and really not surprising as dirty optics will scatter light. I guess the trick is how dirty is too dirty? I would love to see a picture of the mirror before cleaning if you have one.

Sorry I didn’t take a picture of the mirror itself, but it was dirty enough that had you looked down the tube in daylight you would have thought to yourself “wow that’s pretty dirty”.

It is a DSO imaging scope and so it spends many hours on clear nights pointing upwards gathering crud from above, and it needs cleaning about 3 times a year. Its last clean was end of summer 2025.

I just use a no contact method of rinsing under the tap then bathing in hand hot soapy water, followed by another rinse and a blow dry with a hairdryer. I don’t touch the mirrored surface with anything.

This is one of the complaints I have about many, if not most, remote sites. Few of them offer optical cleaning, probably due to damage liability concerns. Your post shows just how important this can be.

My friend has been at several remote sites, all in NM, and not one cleaned his optics. He has sent me photos of what his optics looked like after a couple years and it was pretty shocking. With a bit of water you could have grown crops on them. 🍅🥕🫛🍄‍🟫

Of course my experience has been that NM is one of the worst places for dust and that probably does not help but you would think that part of a hosting service should be cleaning services, either standard or optional.

In my case I make a trip once a year to my remote site in California and clean my own optics. It is not especially dusty so the cleaning interval of one year is about right.

Bill McLaughlin · Mar 30, 2026, 06:57 PM

This is one of the complaints I have about many, if not most, remote sites. Few of them offer optical cleaning, probably due to damage liability concerns. Your post shows just how important this can be.

My friend has been at several remote sites, all in NM, and not one cleaned his optics. He has sent me photos of what his optics looked like after a couple years and it was pretty shocking. With a bit of water you could have grown crops on them. 🍅🥕🫛🍄‍🟫

Of course my experience has been that NM is one of the worst places for dust and that probably does not help but you would think that part of a hosting service should be cleaning services, either standard or optional.

In my case I make a trip once a year to my remote site in California and clean my own optics. It is not especially dusty so the cleaning interval of one year is about right.

Spring is the wind and dust season in NM. You’ll always want to schedule your cleaning visits after that.

I guess it really depends on how vigilant you are with covering the scope every morning. I live on a grain farm and have scopes in my roll off roof observatory and it gets dusty and pollen all around here and I have not cleaned mirrors or lenses much. My remote scope has a flip flat cover also. I wouldn’t have anything remote without a cover.