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Thread: Tips on cleaning eyepieces/filters, anyone?

  1. #1
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    Cool Tips on cleaning eyepieces/filters, anyone?

    I'm sure anyone who has ever owned a pair of binoculars, a camera or a telescope (or worn spectacles/eye glasses for that matter!) knows the agony of keeping those smudge-free and crispy clean, especially when one is eager to share one's passion with anyone (including children) showing some interest in the subject. However, most of your learners have no idea how you cringe in agony when they touch the glass surfaces with their greasy hands (and you yourself occasionally smudge a surface or two). Eye pieces (especially those with short focal lenghts) also pick up greasy spots from eyebrows etc. touching. Then there is also the problem of fogging especially during cooler/colder nights (when the seeing is often at its best) which blurs the view.

    Any advice/tips for cleaning and keeping them clean and fog-free? How serious is the risk of damaging lens coatings by wiping etc.

    One is generally advised to be extremely cautious when cleaning eyepiece glass to avoid scratching or removing some of the optical coatings. Using a blower brush or compressed air to remove dirt particles and a lens pen (with brush and felt tip and sold at most camera shops) is often recommended. Do lens pens differ significantly in quality (safety!) between manufacturers?

    Use of a lens cloth is sometimes advised, but these range tremendously in terms of quality. Are those distributed with spectacles or shades from better known manufacturers such as Oakley, Ray-Ban etc. suitable?

    Are lens wipes (often dampened with alcohol) or aerosol-type foamy lens cleaners (which reportedly also prevent fogging/misting on glass spectacles) safe to use?

    Would these products be equally suitable/unsuitable for binocular objectives and occulars? Or are the coatings used for these more "robust"?

    Do you run the same risk of damaging coatings on filters? (e.g. plain colour/planetary filters as opposed to special light pollution/nebular filters)

    I'm really hoping to get some honest practical advice, based on personal experience, rather than just the run-of-the-mill "safe" recommendations. No-one has to respond to ALL my questions, so any bit of useful, tried and tested information will be welcomed.

  2. #2
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    Dust on a lens is nothing to worry about, you're probably better off leaving that alone. Smudges probably should be cleaned, but you should use a solution designed specifically for multi-coated optics. I'd be leary of using a cloth of any kind personally, or at least a cloth designed for repeated use. I've used a lens pen as well (the Orion version) which seemed to get the job done.

  3. #3
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    Braveheart, my top tip is this (and I guarantee you - it's gonna sound weird, but stick with me). Wash your face before observing, and pay special attention to your eyelashes (!). Most of the annoying specs of grease you get on your eyepieces are from your eyelashes touching the lens, the oils then spread out onto the surface and can make an almost permanent mark. Hot soapy water on your face before observing stops it dead. Prevention is always better than cure, but the general rule for cleaning lenses is only do it when you absolutly have to, because the eyepiece will never be as good again. You obviously also wash your hands at the same time which very much reduces the damage that finger contact can do to lenses.

    There are two main types of mark - grease, which can be avoided as above, and dust. Buy a can of compressed air for the dust. Another top tip - don't shake the can before you use it because even the brands that advertise themselves as "pure air in a can" usually use a solvent based propellant which (I know from bitter experience) is like spraying WD40 on your lenses if you shake before use.

    Regards, Jon.

  4. #4
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    Question

    Quote Originally Posted by redshifter
    Smudges probably should be cleaned, but you should use a solution designed specifically for multi-coated optics. I'd be leary of using a cloth of any kind personally, or at least a cloth designed for repeated use. I've used a lens pen as well (the Orion version) which seemed to get the job done.
    Any brand name solution you can recommend?

    The re-usable cloth presumably risks trapping dirt and scratching?

    Do you actually have evidence/proof/experience that solutions/wipes or whatever can permanently damage lense coatings? I'm not questioning the soundness of your advice, but I would've liked to hear from people who may have had some bad experiences. Often recommendations are made which avoid taking any risk as far as is possible. Nothing wrong with that, but apart from obvious recklessness (wiping lenses with the towel you wash your car's tyres with!), would alcohol wipes/lens cloth etc noticibly damage the coatings? Maybe I should enquire from the manufacturers. Surely they have to test the durability of their coatings during R&D and quality control?

  5. #5
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    Thanks for the response guys. I suspected the eyelashes (especially on short focal lenght lenses and those with a shortl eye relief) and what you say 3rd Rock makes perfect sense, but the problem often arises when you're entertaining friends/family. Maybe one should keep some "WetOnes" or those airline refresher wipes or similar handy and have your observers "freshen-up" before they're allowed to view!

    What about fog/water condensation on cold evenings? Use a portable/flashlight type fan/blower/drier instead of any cleaner which proclaims to render glass "fog-free"?

  6. #6
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    Quote Originally Posted by braveheart
    Any advice/tips for cleaning and keeping them clean and fog-free? How serious is the risk of damaging lens coatings by wiping etc.
    Those are two different things. To keep them from fogging or dewing up when outside, you just need a little heat. Electronics geeks can run a small heater wire up and velcro it around the eyepiece. What I do is periodically swap eyepieces, putting the dewed up one either in a clean warm pocket, or in my eyepiece case where I have a small chemical handwarmer pad that I use on the coldest nights. All you have to do is get the eyepiece a small bit warmer than the air and the dew will go away.

    To keep them clean, do not clean them in the field. I do it at home, and only when they get noticeably dirty. I use clean cotton swabs (made from real cotton, not the fake ones made from nylon or something. I use rubbing alcohol, distilled water and maybe one drop of dishwashing liquid (if they are really grubby). Dip the swab in the liquid, dab lightly and swab in a circular motion. Change to a clean swab frequently. (I've heard stories about Al Nagler cleaning lenses and going through a huge pile of swabs for what might be a single lens).

    There are books that describe how to do this (clean eyepieces), and I think I have referenced them on this Board before. Might try Star Ware or the Backyard Astronomers Guide or some similar book.


    One is generally advised to be extremely cautious when cleaning eyepiece glass to avoid scratching or removing some of the optical coatings. Using a blower brush or compressed air to remove dirt particles and a lens pen (with brush and felt tip and sold at most camera shops) is often recommended. Do lens pens differ significantly in quality (safety!) between manufacturers?
    A blower brush is good to get any chunks of dust off. I avoid compressed air because it might contain chemicals and people have reported ruining their lens or mirror when using it.

    I also avoid a lens pen. Some people love them, but I have damaged an eyepiece with one, so I threw the lens pen away and won't buy another.

  7. #7
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    Quote Originally Posted by braveheart
    Any brand name solution you can recommend?

    The re-usable cloth presumably risks trapping dirt and scratching?

    Do you actually have evidence/proof/experience that solutions/wipes or whatever can permanently damage lense coatings? I'm not questioning the soundness of your advice, but I would've liked to hear from people who may have had some bad experiences. Often recommendations are made which avoid taking any risk as far as is possible. Nothing wrong with that, but apart from obvious recklessness (wiping lenses with the towel you wash your car's tyres with!), would alcohol wipes/lens cloth etc noticibly damage the coatings? Maybe I should enquire from the manufacturers. Surely they have to test the durability of their coatings during R&D and quality control?
    I've been using the multi-coated optics solution I got from the Orion site, I bought a 'cleaning kit' from them quite a while ago. I don't have proof that a solution not specifically designed for multi-coated optics will in fact damage those coatings. However, I have read that that scenario is possible, and I don't want to ruin an eyepeice finding this out the hard way. My reference to not using a cloth multiple times is as you state; to aviod potentially scratching a lens via trapped particles in the cloth.

  8. #8
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    With a nick like braveheart, you should just try various things like gasoline and mayonaise and let us know how it works.
    I forget what my scope manual says but I think it's like a gallon of distilled water with one drop of dish soap. Something like that. Of course it says try not to clean it at all but that's not very helpful.
    One guy tried to tell me to use acetone. I said I definately would not be trying that since that stuff can melt poly urethene paint and plastic.

    Ok my manual from Meade says one part pure isopropyl alcohol, two parts distilled water and one drop of biodegradable liquid dishwashing soap per pint of solution. I was way off. It also says you can just use straight isopropyl (90%). Good luck finding that. The best I find at our drugstore is 70%.
    Last edited by jt-3d; 2006-Feb-05 at 07:40 AM.

  9. #9
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    Quote Originally Posted by redshifter
    I've been using the multi-coated optics solution I got from the Orion site, I bought a 'cleaning kit' from them quite a while ago.
    Do the guys at Orion recommend applying the cleaning solution with a cotton swab or what is included in the kit?

  10. #10
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    Thanx for the tips. I have lens cleaner (for spectcles) containing isopropyl alcohol in small aerosol (compressed air) spray cans. Should I be careful of these as well regarding the possible addition of harmful chemicals like the ones Aurora warns against that are found in compressed air cannistars?

    What about individually sealed small sterile isopropyl alcohol impregnated medical swabs (used to disinfect skin prior to blood sample collection/injection)?

    I have used larger versions of these - lens cleaning tissues with isopropyl alcohol (sold at optomotrists) for spectacles. These impregnated lens tissues dry very rapidly and feel rather thick (almost like writing pad paper!) when dry. By contrast, the medical swabs seem much softer, something similar to nappy liners (diaper liners?) used for babies!

    Any thoughts on these?

  11. #11
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    Quote Originally Posted by aurora
    I also avoid a lens pen. Some people love them, but I have damaged an eyepiece with one, so I threw the lens pen away and won't buy another.
    How was the eyepiece damaged by the lens pen? Could it have had something to do with the quality of the lens pen or its design?

  12. #12
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    Quote Originally Posted by braveheart
    How was the eyepiece damaged by the lens pen? Could it have had something to do with the quality of the lens pen or its design?
    It was one I had bought from Orion.

    I don't know, but it was a Televue eyepiece, so I'm not going to experiment further. I threw the lenspen out, anyway.

    What I do is get cotton swabs, rubbing alcohol, and distilled water. Then when my eyepieces are so grubby that I can no longer stand it (I do attend public star parties and so lots of people look through my eyepieces and I get eyelash stuff and sometimes even a fingerprint despite my best efforts), have an eyepiece and filter cleaning party and go through every piece in my collection and clean all of them that need it. I do this indoors.

    All the other stuff, lens pens, cleaning kits, and such, is just a way for vendors to try to get my money. I don't need any of that, and I am not touching an eyepiece outside anyway, not out in the dust and dew and wind.


    Edited to add that I would recommend a blower bulb. So, if you have to buy something, get one of them. If you really really really think you absolutely have to use compressed air, then make sure you hold the can vertical and that you do NOT shake the can. You want to avoid spraying chemicals all over your lens or mirror.

  13. 2016-Mar-31, 04:49 PM

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