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  1. #11

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    Quote Originally Posted by lxdude View Post
    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 and redo the coatings on the older Leica lenses as part of his repairs/restorations. He would recoat any lens.
    Oh, yeah? I'd sure like to hear more about this. Certainly there's a way to do this without a jillion dollars worth of equipment.

  2. #12

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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.
    Piece of cake. You'll need a vacuum pump, a bell jar and plate, magnesium flouride and a way to vaporise it in vacuo. The same equipment is used to aluminise telescope mirrors.

  3. #13

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    So, MgF2 has a boiling point of 4100 F. That's pretty hot. So you'd need to achieve this temperature and get the gas inside a container with your lens, like cigarette smoke on your windows. Hmm... I need to think this thing through. A bell jar seems easy enough to come up with. A vacuum pump could be the intake side of any air compressor. I saw a fancy machine on ebay for several thousand dollars, but certainly don't have a pile of cash I can peel off a few bills from. Certainly this can be done at home.

  4. #14

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    Quote Originally Posted by Tom1956 View Post
    So, MgF2 has a boiling point of 4100 F. That's pretty hot. So you'd need to achieve this temperature and get the gas inside a container with your lens, like cigarette smoke on your windows. Hmm... I need to think this thing through. A bell jar seems easy enough to come up with. A vacuum pump could be the intake side of any air compressor. I saw a fancy machine on ebay for several thousand dollars, but certainly don't have a pile of cash I can peel off a few bills from. Certainly this can be done at home.
    Wrong. You need a vacuum, not a region of low pressure. A compressor won't even come close. You might be able to modify one though.
    As I said, you need a way to vaporise the stuff in vacuo. That means inside the bell jar under vacuum, so it can condense in the surfaces you want to coat. Think of electricity.
    Last edited by E. von Hoegh; 07-26-2013 at 01:43 PM. Click to view previous post history.

  5. #15

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    So if this process is akin to silvering telescope mirrors, shouldn't I be studying the home-making of telescope mirrors? All I'm saying is certainly this can be done without going into the poorhouse. Thanks.
    BTW--I've got my customer shipping me a quart of methylene chloride on the lens separation project. Acetone and boiling were worthless. My buddy want to put it in his pressure-cooker. I'm a bit more conservative and patient.

  6. #16

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    Sorry OP for hogging your thread. I wonder if this vacuum would have to be as high as the inside of a radio tube.

  7. #17

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    Lets see... An old Nuarc platemaker uses HV to strike an arc with carbon sticks. This causes smoke. The smoke fogs up the vacuum frame glass. Substituting MgF2 in this analogy, you would want the gas from that to deposit on your lens. From that point the coated lens is to be baked to get the deposit like glazing pottery.

  8. #18

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    I once read of someone using something like this:
    http://www.rkdm.com/liquidlense/
    It was better than throwing the lens away.

  9. #19

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    Quote Originally Posted by Tom1956 View Post
    Lets see... An old Nuarc platemaker uses HV to strike an arc with carbon sticks. This causes smoke. The smoke fogs up the vacuum frame glass. Substituting MgF2 in this analogy, you would want the gas from that to deposit on your lens. From that point the coated lens is to be baked to get the deposit like glazing pottery.
    Carbon arcs are typically 35v - 90v, and use high current not high voltage. The vacuum would be a few mm of Hg, not as high as a radio tube. The vapor deposits on pretty much anything cooler than it, you have to shield what you don't want coated. Electron beams have been used to heat the coating materials, remember Fuji EBC coatings?

    The trouble is that anything in a vapor phase will deposit on anything cooler than it, so I don't think a carbon arc would produce a clean enough MgFl vapor to result in a useful coating. It would sure supply the heat though.
    Look into the work done by Katherine Blodgett for Generous Electric.

  10. #20

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    Quote Originally Posted by E. von Hoegh View Post
    Carbon arcs are typically 35v - 90v, and use high current not high voltage. The vacuum would be a few mm of Hg, not as high as a radio tube. The vapor deposits on pretty much anything cooler than it, you have to shield what you don't want coated. Electron beams have been used to heat the coating materials, remember Fuji EBC coatings?

    The trouble is that anything in a vapor phase will deposit on anything cooler than it, so I don't think a carbon arc would produce a clean enough MgFl vapor to result in a useful coating. It would sure supply the heat though.
    Look into the work done by Katherine Blodgett for Generous Electric.
    I am seeing nothing of value on the net to help me figure out any kind of feasible DIY coating. Certainly there must be a way. Seems to me simply getting a layer to deposit would be half the battle. Seems like there would have to be a way to "set" the coating afterwards, lest it would wipe right off. Probably need more time than a few google searches. Haven't even investigated acquiring some raw MgF2 material. Not interested in "multi-coating". An old Rollei lens springs to mind. As far as the OP's question, I believe this thread has already provided the answers with respect to retaining lens curvature.

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