How Often to Clean Optics?

[Hayduke27]

Hey everyone!

I made it out for some stargazing early this morning.  I had a really fun morning of viewing doing not only my normal wanderings about the sky, but also watching Venus, Regulus, Mars, and Mercury rise.  This was my first time viewing Mercury and it did not disappoint.  Anyway, I quickly learned a hard lesson.  Though I had stuck my dew shield in, I forgot to put it on the scope.  Soon not only was my scope dewed-over, but it froze into frost and there was no way for me to clean my lens.  I used a lens cloth to gently try to clear things up, but to no avail.  Anyway, I had binoculars and a spotting scope along as well and still had a great time, but I as I got home a question came to mind: There is some minor smudging on my front lens now from the attempted frost clean-up.  How often do you all clean your optics?  Are you super anal about keeping everything spot free, or do you use things for a little while before giving them a thorough cleaning? Do minor smudges and spots have a noticeable effect on viewing?

[DaveS]

The general recommendation is to clean as rarely as possible, and then with great care.

How badly smudged is your lens? The chances are it's still OK, a lot on here only clean their optics when they can't see through them!

[alacant]

20 minutes ago, Hayduke27 said:

Do minor smudges and spots have a noticeable effect on viewing?

Hi. I had a very dusty mirror; about a year's worth noticeable, used-every-other-night rubbish on it. Cleaned it; blower, dilute detergent and propan-2-ol. Then left to drain on its side after a distilled water bath. Absolutely no difference!

HTH.

[Alien 13]

With lenses the odd mark and light dust has little effect, I however inspect them regularly and clean them if any residue or other organic contaminants are found, nothing worse than coating/glass eating critters.

Alan

[Peter Drew]

My cleaning regime is:-   Mirrors when I can't see my face in them, lenses when I can write my name in the dust on them.  

[ronin]

Clean when you decide you need to. The real thing is to take care. There is no specific state they need to get to to be cleaned.

Glass is fairly robust material, on lens the fear may be scratching them but which is best - not to clean for a time until there is a build up of crub that could cause a scratch or do it often when one of the cleanings may cause a scratch.

Mirrors are I suspect a bit different as you have an SiO2 overlayer for protecting and that protection layer may be poor.

Personally I like them clean. After all I trust my life to a rubber scraper going over the screen of a car with me driving it at 100kph.

[Dave In Vermont]

In other words, you're not actually considering cleaning a mirror - you're considering cleaning delicate optical-coatings that are intentionally deposited on a mirror. I try my best to only rely on a strong blower (like a 'Rocket-Blower') and then, maybe, a super-fine optical brush.

Dave

[Alien 13]

I do like the CO2 fire extinguisher approach to cleaning mirrors, a few big scopes do this..

Alan

[Nyctimene]

18"   Obsession, bought 1999: mirrors cleaned three times;

8" Travel dob, bought 2007: cleaned once;

14x100 Wachter binoculars, bought 1979: still uncleaned (but well kept) objectice optics.

Stephan

 

[LukeSkywatcher]

My 90mm refractor (lens scope) bought 9 yrs ago: Never cleaned as was only used a handful of times before going into retirement.

My 130mm reflector Heritage Dob (mirror scope) bought about 8 yrs ago: Never cleaned.  

My 70mm refractor Travelscope (lens scope) bought maybe 6 yrs ago: Never cleaned.

My 200mm SCT (lens scope) bought 5 yrs ago: Never cleaned.

If any cleaning has been done on any of them (and even on my 10x50 and 20x90 bins)..........it has just been a rocket blower to remove any crud.

 

 

[Uranium235]

I clean my fracs and lenses whenever I feel dust or grime may interfere with flat field calibration. As for primary or secondary mirrors, Ive done my 130pds twice and never cleaned the 200pds (its never been out enough!).

But as for cameras and filters, Im pretty OCD about keeping those clean - otherwise it renders my flats library useless.

[onlyme]

What I do is remove primary cell, leave mirror in cell, tilt cell 30 degrees (or so) with one edge of cell leaning on a folded towel on floor of bath, run distilled water over mirror face to wash off dust, leave cell tilted to drip/air dry with a clean plastic bag over the mirror so it doesn't gather dust as it dries.

[Dave In Vermont]

1 hour ago, onlyme said:

What I do is remove primary cell, leave mirror in cell, tilt cell 30 degrees (or so) with one edge of cell leaning on a folded towel on floor of bath, run distilled water over mirror face to wash off dust, leave cell tilted to drip/air dry with a clean plastic bag over the mirror so it doesn't gather dust as it dries.

A caveat on the plastic-anything on a mirror, lens: A plastic-bag rested on top of my secondary for awhile after I disassembled my scope for some work. When I removed the bag, it had deposited a strange, blue film on the secondary - in a very trippy-pattern replete with inlets and coves. It looked like the Saturnian Moon 'Titan!' Only in blue, rather than orange.

Advice: Don't let plastic touch your mirrors or lens. I used 91% iso-propanol to remove this muck. Thankfully it's okay now.

Dave

[onlyme]

2 hours ago, Dave In Vermont said:

 

Advice: Don't let plastic touch your mirrors or lens. I used 91% iso-propanol to remove this muck. Thankfully it's okay now.

Dave

Indeed so Dave, I failed to be clear on this point, the bag is tented (so to speak) above the mirror without actually touching it.

I used Isopropyl alcohol but found it leaves a certain residue, not so sure what causes it, perhaps caused by the alcohol reacting with deposits due to impurities from the containing receptacles used, also alcohol evaporates leaving behind any diluted deposits, while distilled water runs off carrying away in the process any diluted deposits.

What has always left my mirrors sparkling clean is the use of distilled water.

[Dave In Vermont]

44 minutes ago, onlyme said:

Indeed so Dave, I failed to be clear on this point, the bag is tented (so to speak) above the mirror without actually touching it.

I used Isopropyl alcohol but found it leaves a certain residue, not so sure what causes it, perhaps caused by the alcohol reacting with deposits due to impurities from the containing receptacles used, also alcohol evaporates leaving behind any diluted deposits, while distilled water runs off carrying away in the process any diluted deposits.

What has always left my mirrors sparkling clean is the use of distilled water.

After the Attack of the Blue Mist! - I wouldn't suggest even tenting the plastic. Sterile surgical-cotton pads - sure! Plastics do a nasty thing called "outgassing" that can travel airborne. It's bad enough we even let these materials in our homes.

Regards iso-propyl - I'm an organic-chemist and always look for the highest grade chemicals available. U.S.P. or bust. But that over here in the U.S. Nonetheless, I don't let it dry onto the mirror - I pour it at an angle and blow it off with my "Rocket-Blower."

Dave

[JOC]

It hasn't been suggested, but if you can get to the mirror I imagine a aerosol of 'canned' air-duster might help.  I use this on computers - the most important thing to remember when using it is to keep the can upright though, or it will shoot liquid organic solvent propellant out over everything - though if this were to happen it does all evaporate quite nicely.

[25585]

Got an old Fullerscopes catalogue. The late great Dudley's advice for mirrors is flakes of non-caustic plain soap or Lux completely dissolved in warm water to immerse the mirror in and swish. Rinse off with de-ionised water, then soak up the droplets individually with blotting paper or soft absorbent cloth.

[LukeSkywatcher]

"After the Attack of the Blue Mist! 

LOL...........

When i bought my SW Heritage 130P from FLO a few yrs ago, as soon as i un-boxed it, the primary mirror turned blue. I emailed them and they said this was completely normal and to give it a few mins to fade.

 

[Dave In Vermont]

Your 'blue' wasn't like this, was it?

 

 

Yuck!

Dave

[mikeonnet]

Looks like your PC monitor could also do with a clean!

[onlyme]

I wonder what kind of plastic bags you have in the states, and if the concentrated alcohol vapor reacted with the plastic used.

I do not see why anything stronger than distilled water is needed, unless your mirrors play rugby on a regular bases, then a few added soap flakes to the distilled water should do the trick.

[ronin]

The other day I saw "Microfibre bed sheets". So as you hug the scope and turn over during the night they get a clean. 

[Buzzard75]

I think my eyepieces are going to need a little bit of a cleaning. I took my scope to a star party last weekend and there were a couple of kids there who insisted on touching the eyepieces every time they went to look through them, even after repeatedly being told no to even touch the scopes. I didn't look at them the next day, but I'm guessing there's a few smudges on them. Will regular eyeglass cleaner and a clean microfiber work for something like this or is there something else that is recommended?

[onlyme]

1 hour ago, Buzzard75 said:

Will regular eyeglass cleaner and a clean microfiber work for something like this or is there something else that is recommended?

That is what Tele Vue suggests you do, I say do what they say but substitute the suggested alcohol with distilled water, and replace the Q-tip used after each wipe.

Next time you star party with the local brats, buy yourself a couple of cheap Chinese eyepieces from a Chinese vendor, and get them sent to you on the slow boat (for cheapness sake since you are in no hurry for them I assume).

Gold Lines are worth considering, you be surprised how good they are for what they cost.

[Ricochet]

On 22/09/2017 at 14:13, Buzzard75 said:

I think my eyepieces are going to need a little bit of a cleaning. I took my scope to a star party last weekend and there were a couple of kids there who insisted on touching the eyepieces every time they went to look through them, even after repeatedly being told no to even touch the scopes. I didn't look at them the next day, but I'm guessing there's a few smudges on them. Will regular eyeglass cleaner and a clean microfiber work for something like this or is there something else that is recommended?

First use a bulb blower to remove any particles and then spray the lens cleaner onto the cloth rather than directly onto the lens.