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  1. #1
    Jon Goodman's Avatar
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    Cementing lens elements

    Yesterday somebody sent an email asking how difficult it was to separate and re-cement lens elements. A couple of years ago I wrote some notes and posted them to Fotomozaic. You can see them here (along with a few other notes I wrote):

    http://www.fotomozaic.ro/

    Hope they're helpful. If anyone has any questions or needs a small bit of balsam, please let me know. Note: you can use the same balsam used for microscope slides. Honestly speaking, there are many different ways to successfully do this and they all will work. Some people use UV cured cement, and it will work fine, however there are reasons I don't like it (and I should mention I've repaired watches since...well for decades). If you read comments on the internet, you are likely to see dire warnings about lens element alignment. Trust me, you can use your tongue to sense proper alignment. It is able to detect differences of less than the thickness of a cat hair.
    Jon

  2. #2
    lxdude's Avatar
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    Quote Originally Posted by Jon Goodman View Post
    Yesterday somebody sent an email asking how difficult it was to separate and re-cement lens elements. A couple of years ago I wrote some notes and posted them to Fotomozaic. You can see them here (along with a few other notes I wrote):

    http://www.fotomozaic.ro/

    Hope they're helpful. If anyone has any questions or needs a small bit of balsam, please let me know. Note: you can use the same balsam used for microscope slides. Honestly speaking, there are many different ways to successfully do this and they all will work. Some people use UV cured cement, and it will work fine, however there are reasons I don't like it (and I should mention I've repaired watches since...well for decades). If you read comments on the internet, you are likely to see dire warnings about lens element alignment. Trust me, you can use your tongue to sense proper alignment. It is able to detect differences of less than the thickness of a cat hair.
    Jon
    You lick cats?
    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.

  3. #3
    Jon Goodman's Avatar
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    Only when I want to make sure my tongue is still working correctly.
    Jon

  4. #4

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    nice write up. I prefer to use acetone for separating the elements. I worry about cracking the glass with the heat method. Typically I find it takes about a week for the acetone to work its way through enough to separate the glass.

    Dan

  5. #5

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    Cyanoacrilates

    In the 60's Kodak developed what we now call "majic glue", Hot Stuff, crazy glue, etc. (the original formula was called Eastman 910) and it was developed specifically for gluing lens elements together because of some of the undesireable properties of balsam.

    It is optically clear, VERY thin, self-wicking, does not grow fungus, cheap, stores in the frig, easy to work with after some practise.

    It does not activate until it comes into contact with moisture, so keeping two lens elements absolutely dry will give time for repositioning as needed. An spray 'activator' can be used to kick it over when desired.

    I have not used it to glue lens elements but have used a lot for other purposes: machine shop, inventions, etc. It can be the right stuff for the right reasons.

    Perry

  6. #6

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    I've used two V-blocks and a small cast iron surface plate to align elements.

  7. #7

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    E., given your interest in Dagors and such you need to know that according to Eric Beltrando M. Kiritsis, Boyer's last owner, cemented Beryl cells by hand. Held the glasses between his fingers, didn't use V-blocks.

  8. #8

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    Quote Originally Posted by Dan Fromm View Post
    E., given your interest in Dagors and such you need to know that according to Eric Beltrando M. Kiritsis, Boyer's last owner, cemented Beryl cells by hand. Held the glasses between his fingers, didn't use V-blocks.
    I was glueing a Rapid Rectilinear. I'm sure I could align the edges by feel, but I liked the idea of letting the balsam set with no chance of it being knocked out of alignment. You know, belt & braces.

  9. #9
    Mustafa Umut Sarac's Avatar
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    Artisans have secrets and using your tongue is one of them. Due to heavy smoking past two years , I dont think I am healty as past and cigarettes are chemical burning my face and mouth. I found you are watchmaker Jon and I read many books on them. I think your hands turned to an micrometer. I think lens centering might get help from an optical unit , may be interferometer.

  10. #10
    Mustafa Umut Sarac's Avatar
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    Because , optical designer and his her team invests years to develop a lens , machinist having hard times to match a precision 5 or more digits after the point. Every deviation , like the ruby or pinions precision on a watch will add you lots of seconds per month.

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