Over cleaning your optics

[spaceboy]

Hi All

I understand that for the best part most members wouldn't even contemplate cleaning their optics and continue to enjoy the views all the same. I just wondered for those who have taken on the task did they find it difficult to resist the perfection pitfall of over cleaning their optics?

I think it is so breed in to us to have things spotlessly clean and shiny it is sometimes hard to accept that the bit of dust left on your mirrors after cleaning or the residue of cleaning fluid left on your eyepiece / refractor lens.

Is it not more beneficial to tend to your optics with kid gloves and accept that they are at least cleaner than when you started, leaving some reminisce of that what made you want to clean the optics in the first place than to risk being heavy handed in the attempt to return the optics to there former glory ?

Or is the whole idea to return the optics to there former glory when you take on the stressful task of cleaning optics in the first place ? At the end of the day which benefits most ? clean optics or ones free from any tell tale whispers of over zealous cleaning ?

My own thoughts are that dust, grime, condensation and dew is an unavoidable part of exposure to the elements. What is avoidable is your own desire to apply that little bit more pressure to your optics to remove that stubborn dust or smear and so risk scratches as a result.

[chiltonstar]

Risk assessment required each time maybe?

I've had anti-reflection coatings on lenses damaged because I've left tiny specks of dirt (maybe power station ash) on them and when dew has formed, it has attacked the coating at that point. For that reason, I give the front of my scopes a regular blast with clean air to remove as much as possible and then, maybe, and only occasionally, a clean with an optical wipe wetted with IPA or similar.

Chris

[Charic]

hi spaceboy.......I`m not overly concerned with the mirrors, unless a pigeon has done a dirty in there, or coffee stained till its tacky (grossly exaggerated)

I've removed my mirror cell several times, just for the fun of it, and as an aid to learning more and being confident with the build, set-up and calibration of the telescope, but as yet not washed it. I have used the compressed air cans, used for cleaning out PC's, and that shifts  surface dust, but I've been warned that the contents may have chemical impurities that could harm the mirrors protection?  so stopped using that method. I do often clean the eyepieces though. I just use Zeiss lens wipes as/when needed. The Skywatcher mirrors are protection coated, so as long as your gentle with the cleaning, there shouldn't be a major problem. Just rinsing  and dragging surgical cotton wool cant destroy the surface, even after several washes IMHO.

Looking at your mirror from the Aperture opening doesn't bode well, as the image you see is magnified, and the dust looks worse. 

[Mike73]

Living in Cornwall the problem I have is the sea air, my favourite observing spot is on a cliff top overlooking the English Channel which really is great but I'm well aware that a build up of salt on the mirror surface aint gonna do it much good!

I'd say that roughly every 3 months I take my primary out and run it under the shower for 5 minutes just to try and stop any salt build up, luckily its a very easy job to do and takes maybe 20 minutes in total.

I think theres a fine line between taking care of your mirror and over cleaning it. If I lived inland I'd probably clean it once a year but I think that if I left it that long living where I live it will probably be doing some harm to the mirrors surface.

[Grotemobile]

This is what I use to to clean

my lenses with.

http://www.firstlightoptics.com/misc/baader-optical-wonder-fluid.html

I just use the cloth & the wipes,

that are used for computer screens.

Steve.

[coulthamst]

Only just noticed by using the link provided by Grotemobile - Baader Optical Wonder Fluid is NOT recommended for use on Newtonian mirrors by the makers. Caveat emptor.

[ronin]

With mirrors you have to accept the idea that they have a life span. It may be up to 10 years but I suspect that 6 or 7 is more realistic, and I suppose less if the scope is kept outside in a shed or similar. All that rain is acidic and therefpre so is the moisture.

Cleaning is a choice for the owner, leave a mirror and general crud builds up making the chance of a mishap greater when it is cleaned more likely. Clean them often and you are wearing away at the surface and the surface is a very thin layer.

Interesting that Baader do not recommend the stuff for mirrors . How many time is that advice given out. So the dish washer it will have to be then. :eek:  

[Moonshane]

I occasionally clean my eyepieces but carefully and rarely and usually only when they look grubby or I can see the bits when e.g. looking at the moon or sun (or when selling sometimes).

I have never cleaned my 16" mirror (owned it for four years) and rarely clean mirrors unless selling or there's a lot of gunk. Even then I don't worry about the odd spot and agree with you that getting off the bulk is what's important not the stubborn remnants which can cause problems if over-enthusiastic cleaning creates damage.

I may possibly clean my 16" mirror this year but it's not that mucky and is a closed tube affair so stays that way pretty much.

on longevity of coatings, I have a (I think) late 1980s / early 1990s OOUK 12" f4 mirror which is still ostensibly shiny but is showing pinholes when a light is shone through the back. It still provides superb planetary images and reveals DSOs galore so I think although there's little doubt that mirrors deteriorate from day one, it may not be noted at the eyepieces for decades and even then......

[ChrisLX200]

The only parts I keep as near spotless as I possibly can are the CCD camera window, the filters, and the focal reducer. I don't recall ever looking at the objective of my NP127is (I must do that sometime - there's probably glass at that end). I wouldn't clean the objective though. The primary on my 12" Newt has not been cleaned in 15yrs but I always keep it covered unless in use.

ChrisH

[spaceboy]

Thanks for the replies guys. I had no option other than to give my mirror a clean as per this vid https://www.youtube.com/watch?v=8TObET2F-EA as I felt there was a little too much of a mixture of dust and dried dew / condensation on the surface.

I couldn't have been happier with the whole outcome IE: no damage to the mirror and a noticeably cleaner appearance, but why is it there always seem to be those parts that cleaned better than others and leave you with that irritating itch.

I admit from previous experiences I have learned better than to mess for 1, after several long observing sessions the layer of dust will no doubt be uniformed once again and 2, if it ain't broke "trust me" don't try to fix it !!!

[Charic]

Thanks for the replies guys. I had no option other than to give my mirror a clean as per this vid https://www.youtube.com/watch?v=8TObET2F-EA as I felt there was a little too much of a mixture of dust and dried dew / condensation on the surface.

I couldn't have been happier with the whole outcome IE: no damage to the mirror and a noticeably cleaner appearance, but why is it there always seem to be those parts that cleaned better than others and leave you with that irritating itch.

I admit from previous experiences I have learned better than to mess for 1, after several long observing sessions the layer of dust will no doubt be uniformed once again and 2, if it ain't broke "trust me" don't try to fix it !!!

.......All part of the fun 

[Owmuchonomy]

Thanks for the replies guys. I had no option other than to give my mirror a clean as per this vid

 as I felt there was a little too much of a mixture of dust and dried dew / condensation on the surface.

I couldn't have been happier with the whole outcome IE: no damage to the mirror and a noticeably cleaner appearance, but why is it there always seem to be those parts that cleaned better than others and leave you with that irritating itch.

I admit from previous experiences I have learned better than to mess for 1, after several long observing sessions the layer of dust will no doubt be uniformed once again and 2, if it ain't broke "trust me" don't try to fix it !!!

Yep, that's the video I followed. There are others but they apply more vigorous methods. The critical item is the distilled/deionised water which on use left my mirror without a single water mark. My mirror had culture spots of organic material so I felt justified in cleaning it. If it had been dust I would have blown it clean with a compressed source and left it at that.

[moriniboy]

This mirror from the 80's still works fine, might consider re-coating sometime in the future though when it gets really bad 

[LukeSkywatcher]

There's a scope at the Kielder observatory with a 20 inch mirror (i think its 20) and it was on the S@N a couple of yrs back. The mirror is absolutely filthy but it is still in use. I mean its so dirty its yellow and looks coated in nicoteine. I ve always said that i'd buy a new scope before i'd attempt to clean. Thankfully the only scope i have with a mirror open to the elements is a Heritage 130P................so not expensive to replace.

[spaceboy]

I recently came across this http://www.distilleddeionizedwater.com/deionized-water-vs-distilled-water/ which would seem to suggest Deionized water to be more pure water than distilled water  If so would deionized water not be the better choice for rinsing mirrors ??? I'm aware that deionized water is sold for steam irons which makes sense as you don't want to risk staining your clothes every time you iron them or clog up your iron.

[Crossway]

I once took loan of an 8" reflector from my local Astro Society and  was astonished to be  advised,  not to attempt to clean the primary mirror which to my eyes was rather dusty.   The  member in charge of  club hardware, including the main very large reflector at their observatory  told me that in their experiance  washing and cleaning the mirrors did not make much of a difference.  I don't know whether this is a general view of societies but it is an interesting one.

[Paul73]

I cleaned my primary.

It got dirty again. They seem to settle fairly quickly to a base level of grubbiness.

Paul