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  1. #1

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    Polishing lens glass

    I have and ancient CC Harrison full plate lens which I've been using for two years. It does a beautiful job when I use strobe but does have a ton of cleaning marks on it so outdoors it's very soft and hazy. I'm wondering if there's a good way of cleaning up these marks and making it more useable for natural light?

  2. #2

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    Quote Originally Posted by illumiquest View Post
    I have and ancient CC Harrison full plate lens which I've been using for two years. It does a beautiful job when I use strobe but does have a ton of cleaning marks on it so outdoors it's very soft and hazy. I'm wondering if there's a good way of cleaning up these marks and making it more useable for natural light?
    This isn't a DIY job unless you have a lot of skill and at least some experience. You would have to preserve the original radius of curvature while maintaining centration of the surface, to a tolerance of about nothing.

  3. #3

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    In my experience cleaning marks tend to be rather deep. Probably too deep to be fixed without professional help. The front element would probably have to be reground or replaced. You can try very carefully filling in each deep scratch with a bit of black paint. This will prevent the flare problem outdoors. The lens will look like hell but work better.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  4. #4

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    Also, I forgot to mention that a good lens shade of the compendium type will make a great, perhaps huge, difference.

  5. #5

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    If you are daring, make good friends with a hobbyist telescope maker and give it a go.

    It ain't rocket science, just something that takes care and attention to detail.

  6. #6

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    [QUOTE=vysk;1526432]If you are daring, make good friends with a hobbyist telescope maker and give it a go.

    Yup, glass pusher here, but a long time ago. You need to make a pitch lap and try cerium oxide as a polishing agent. You mold the soft pitch with the lens itself thus perserving it's radius. The finer marks should polish out, the deeper gouges won't. Of course the lens element has to be removed to work it on the lap. The trouble is getting only small amounts of the materials you need.

  7. #7

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    [QUOTE=pen s;1527833]
    Quote Originally Posted by vysk View Post
    If you are daring, make good friends with a hobbyist telescope maker and give it a go.

    Yup, glass pusher here, but a long time ago. You need to make a pitch lap and try cerium oxide as a polishing agent. You mold the soft pitch with the lens itself thus perserving it's radius. The finer marks should polish out, the deeper gouges won't. Of course the lens element has to be removed to work it on the lap. The trouble is getting only small amounts of the materials you need.
    One can buy small amounts of diamond lapping/polishing compound, pretty reasonably, from McMaster-Carr.

  8. #8
    Ian Grant's Avatar
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    Cerium oxide isn't expensive, I bought some from a Lapidiary suppliers earlier this year and they told me they only sold it these days to amateur telescope manufacturers and similar. I wanted to try some on a Ground glass screen and found that it polished the glass rather quickly.

    Ian

  9. #9

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    Now, if only somebody has come up with home-made lens coating, we've got it made.

  10. #10
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    Quote Originally Posted by Tom1956 View Post
    Now, if only somebody has come up with home-made lens coating, we've got it made.
    If it's an ancient lens, it had none originally. And single coatings are available. I can't remember now the Leica guy who could repolish the older Leica lenses and redo the coatings as part of his repairs/restorations. He would recoat any lens, as I recall.
    I do use a digital device in my photographic pursuits when necessary.
    When someone rags on me for using film, I use a middle digit, upraised.

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