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Thread: Refracctor Lens Cleaning

  1. #1
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    Default Refracctor Lens Cleaning



    Hi everyone,

    I have read several posts covering cleaning the lens of a refractor.gently blow Gently blow with air, maybe use a camel hair brush, then diluted alcohol mist and wipe with a lens cloth. Its amazes me how much debris collects on the lens after only several hours.

    What I haven't seen is how to clean the inside of the lens cell. For some reason, I have specs of dust there too! I keep things capped up when I don't have an eyepiece or camera attached, but I still see dust collect there.
    I tried connecting several straws together and crudely connecting them to a canned air can, but this is very awkward.

    Does light lens dusting really affect the view or imaging quality?

    I'm sure that others have the same issue. What do y'all do?

    Thanks,
    Jim
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  2. #2
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    Default Re: Refracctor Lens Cleaning

    In my short experience with visual obs I have never noticed the dust on my objective lens while observing. Its mostly when I'm just fondling my scopes that I focus on it and I used to worry about it. Now I only puff air over to move the loose stuff off...never much there.
    I found a tiny spec of dust on the inside of my ES 127 APO that used to give me nightmares. But that too has passed. The little speck is there but never seen at the eyepiece.

    So...I guess I have become more relaxed about that stuff. I take care of things but I don't overdo.

    Anyway I would be very very careful about sticking anything down inside my tube.

    Clear skies to you Jim. And happy Thanksgiving!
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  4. #3
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    Default Re: Refracctor Lens Cleaning

    The only way to clean the lens on the inside is to remove it from the scope. Gabby is our resident expert when it comes to that, she gave me plenty of good advice when I did mine.
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    Default Re: Refracctor Lens Cleaning

    Taking the lens cell apart and realigning is easy for doublets but I would not suggest it for a triplet unless you are very experienced and have the equipment to align the lens properly.
    If you definitely need to have it cleaned then make arrangements with the company you purchased it from if it is a triplet.

    Please do not use canned air to clean the inside lens. If the can gets shaken at all you could spray the liquid directly onto the lens.
    Clean room/ optical quality canned air is much different than the department store product.

    It will take a lot of dust to affect the views at all but if you feel you do need to clean the back of the lens then get a thin dowel and tape your soft brush to it.

    Two universal constants: Dust and water will go wherever they want, even if you think it is sealed
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    Default Re: Refracctor Lens Cleaning

    Quote Originally Posted by Gabby76 View Post
    Taking the lens cell apart and realigning is easy for doublets but I would not suggest it for a triplet unless you are very experienced and have the equipment to align the lens properly.
    If you definitely need to have it cleaned then make arrangements with the company you purchased it from if it is a triplet.

    Please do not use canned air to clean the inside lens. If the can gets shaken at all you could spray the liquid directly onto the lens.
    Clean room/ optical quality canned air is much different than the department store product.

    It will take a lot of dust to affect the views at all but if you feel you do need to clean the back of the lens then get a thin dowel and tape your soft brush to it.

    Two universal constants: Dust and water will go wherever they want, even if you think it is sealed
    Thanks Gabby,
    I will not attempt to clean the inside of the cell unless it gets really dirty. Its a triplet and I wouldn't dare remove the cell. The dowel and soft brush would be the best approach if absolutely necessary. Especially if the optical degradation is insignificant. Its really not all that bad.
    Great advice, thanks!


    Quote Originally Posted by Don Quixote View Post
    In my short experience with visual obs I have never noticed the dust on my objective lens while observing. Its mostly when I'm just fondling my scopes that I focus on it and I used to worry about it. Now I only puff air over to move the loose stuff off...never much there.
    I found a tiny spec of dust on the inside of my ES 127 APO that used to give me nightmares. But that too has passed. The little speck is there but never seen at the eyepiece.

    So...I guess I have become more relaxed about that stuff. I take care of things but I don't overdo.

    Anyway I would be very very careful about sticking anything down inside my tube.

    Clear skies to you Jim. And happy Thanksgiving!
    Thanks DQ! I tend to be '****' and picky about things. Good advice, let it slide!
    Enjoy your day tomorrow also! I am doing some cooking right now.
    Being close to New Orleans and a Saints fan, I'm looking forward to a good game vs. the Falcons tomorrow evening too!

    Clinton, thanks for the advice. I will not concern myself too much with it for now.

    Thanks All!

    Jim
    Scopes: Explore Scientific ED102 Triplet APO, Celestron Nexstar 130 SLT.
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    Default Re: Refracctor Lens Cleaning

    Hello Jim,

    if it is the triplet as in your signature, then I would first take a closer look on the lens surfaces.
    Switch on some bright light shining on the telescope lens, and use a magnifying glas to see what these dots are about,
    and on which surface they exactly are.

    These dots looking like dust may be eventually points, where the multicoatings on the inner lens surfaces are disintegrating. I have seen it quite a few times.
    This may happen when the manufacturer does not deposit hard protective coatings (like SiO2 or other materials),
    on top of the antireflex multicoatings on lens surfaces,
    or when the lens surfaces have not been properly cleaned before depositing the antireflex multicoatings.

    So far you don't have an access to a clean room, and so far you can't make an artifical star test to confirm that the triplet has been assembled correctly after you took it apart, I would not recommend you to open the lens cell of a triplet.

    Best,

    JG
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    Default Re: Refracctor Lens Cleaning

    The advice above given is good. A few dozen particles on the inside of the lens can do no harm to the image.

    Several owners of refractors, Maks and SCT's called in my help for cleaning their optics. They were terrified by the little dust particles. I could not bring them to other thoughts, so I helped them. Years later they admitted that all the noise around these particles was not necessary at all. One just can't see it.
    My own 4 inch Vixen ED f/9 is thirty years old. Has particles in it. Never been cleaned by me, although I easily could.
    Best advice is: Lean back and relax. By the time you can notice the inside dirt you will be 150 years older.
    Telescopes in Schiedam : SW 150 F/5 Achromat, SW Evostar 120ED F/7.5, Vixen 102ED F/9, OMC140 maksutov F/14.3, SW 102MAK F/13 on Vixen GPDX.
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