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Thread: Lens cleaning question: caked on dust

  1. #1

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    Lens cleaning question: caked on dust

    Hello,

    I am embarrassed to admit that the single best piece of glass I own has endured a terribly unfortunate circumstance. My enlarging lens, a Schneider APO-Componon HM 4/150, sat in open air for 10 years without the lens cap for the rear element.

    As a result, the rear lens element has a wealth of dust on it. I imagine the dust to be slightly caked onto the lens surface by changes in humidity.

    Embarrassing as this is, I am delighted to be returning to the darkroom. Would anyone care to suggest the best way for me to clean this lens? Or is this a clear case of sending it off to a pro.

    Thanks in advance,

    Lewis

    ps. In the pictures below, the crud immediately around the outside of the lens is supposed to be there. It is foam and does not need to be removed. I assembled a makeshift lens alignment device, modeled after a commercial product sold by Calumet or Zone VI or somebody. The foam belongs to that mechanism and should not be causing any problems. Thanks again!

    pps. I cleaned the back of the lens board and added a third pic of the lens. The first view from an angle makes the lens look a bit worse of than it really is.
    Last edited by LewisDowney; 15-Jan-2008 at 09:30. Reason: added third picture

  2. #2

    Join Date
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    Washington, D.C.
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    Re: Lens cleaning question: caked on dust

    1) Blow off the loose dust with a rocket blower or similar.

    2) With a high quality lens cleaning fluid, dampen (not drench) some lens tissue and lightly swab in a circular motion starting at the center. Frequently change the tissue and use only light rubbing motions. Work your way out to the periphery of the lens element. Multiple light applications will be better than rubbing too hard. Good luck.

  3. #3

    Re: Lens cleaning question: caked on dust

    When I got my Holmes, Booth & Haydens lens, it had quite a layer of protective dust on it. Ended up using a blower brush first, which really didn't remove much of anything. Then I took Kodak Lens Cleaner, and let it slosh around on the surface. That got even more off. At that point, it was possible to disassemble the lens, and do a more proper cleaning. The result was perfectly clear optical elements . . . seems the dust really did protect the lens, for however many years it sat unused (lens dates from 1854). So take your time with it, and don't be sparse with the lens cleaner.

    Ciao!

    Gordon Moat Photography

  4. #4

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    Re: Lens cleaning question: caked on dust

    Hey thanks Barry and Gordon.

    If it helps, we have a small ultrasonic cleaner. I could remove the back portion of the lens and hold it above the bottom of the ultrasonic cleaner for a few minutes. I am a little worried that the liquid will penetrate to the interior of the lens though. The liquid is water with a mild detergent, not a solvent.

    For that matter, I could replace the mild detergent with plain water. Even with plain water, my concern is that the ultrasonic cleaner might cause some of the fluid to work its way to the interior of the lens.

    Thoughts? I am not prone toward disassembling the lens down to the glass elements.

    -Lewis
    Last edited by LewisDowney; 15-Jan-2008 at 11:41. Reason: clarity

  5. #5

    Re: Lens cleaning question: caked on dust

    If you don't want to disassemble the lens, then I would suggest just using lens cleaner. The only ultrasonic cleaner I am familiar with is one I use to use with Rapidograph pens, but the solvent was something I don't think would work well on lenses. Lens cleaner fluid would be a much safer choice.

    Ciao!

    Gordon Moat Photography

  6. #6

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    Re: Lens cleaning question: caked on dust

    Yeah, maybe it is a perfectly ordinary cleaning situation; albeit one that requires extra delicacy.

  7. #7

    Join Date
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    Alaska
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    Re: Lens cleaning question: caked on dust

    Quote Originally Posted by AtItAgain View Post
    .....we have a small ultrasonic cleaner. I could remove the back portion of the lens and hold it above the bottom of the ultrasonic cleaner for a few minutes. I am a little worried that the liquid will penetrate to the interior of the lens though. The liquid is water with a mild detergent, not a solvent......
    I would NOT use an ultrasonic cleaner on a glass element. With the elements in the lens, use regular lens cleaner, or just plain distilled water. If you remove the lens, use a mild dish washing detergent under running warm water, then rinse with distilled water. Use a very soft cloth, or better, a micro-fiber cloth designed for lens cleaning.

  8. #8
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    Tim from Missouri
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    Re: Lens cleaning question: caked on dust

    Sounds like good advice so far, but you might want to try 'lifting' the dirt off with the first several applications of lens cleaner and tissues rather than wiping or swirling. Those activities could result in scouring into the coating or glass if there is even the thinnest grit in the dust.

    By moistening the tissue and dabbing and lifting over many applications, you can get the really bad stuff off and then, when it is almost totally clean, use a camel hair brush to get rid of the final bits and then go with the moistened lens tissue in a normal wiping final clean.

    Good luck.

    Tim
    "One of the greatest necessities in America is to discover creative solitude." Carl Sandburg

  9. #9

    Join Date
    Jan 2006
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    nuevo mexico
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    Re: Lens cleaning question: caked on dust

    Send it to me.

    I will clean it and send it back in about 6 months.

    (if you want to sell it let me know)

  10. #10

    Join Date
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    Lund, Sweden
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    Re: Lens cleaning question: caked on dust

    A lot depends upon the composition of the dust. Around here, we get a lot of fine inorganic topsoil dust blown off the surrounding farmland, and even the purest clean room wipes and reagent grade methanol will scratch a lens if they trap a grain of grit and scour it across the surface.

    There are specialised polymers which you can pour onto optical surfaces, allow to set, and then peel off, taking the dust and grit with them. Collodion is very effective when used like this, so if you or a friend are into wet plate work you could use that. Otherwise, there is a company that used to be called Opticlean that sells a polymer well-regarded by the laser folk whose brains I pick. www.opticlean.com

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