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Thread: Glue Separation?

  1. #1

    Join Date
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    Glue Separation?

    I've been looking for a lens for my new Shen-Hao 4x5 on eBay and have come across several statements similar to this one over the course of the past month or two (from an auction for a Rodenstock Sironar 150mm f/5.6 with no reserve and a starting bid of $49.99):

    "This Lens is in Excellent condition with no blemishes on the casing. There is glue separation within the lens which can be overhauled, however this minor flaw has NOT interfered with picture quality!"

    First, it seems to me that a lens cannot be in "Excellent" condition if there is glue separation among the elements. Second, it also seems to me that such separation WOULD interfere with picure quality, at least lowering the amount of light that gets through the lens to the film. Finally, I wonder what an "overhaul" of such a lens would cost and if it is so prohibitively expensive that the lens isn't worth buying at any cost?

    Best wishes,

    Craig

  2. #2

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    Re: Glue Separation?

    Unless it is an expensive or unique lens, stay away. John Van Stelton at Focal Point, Tim Sharkey at LensN2shutter, Ultra Flat can recement elements, but John charges about $180 per "joint". which would be the price for the Sironar (cemented elements are doublets).

    So you'd need to get about $250 off the price of a $250 lens to break even after shipping and such. And that's assuming everything else is perfect, always a risky assumption with old lenses.

    Oh yes, and that assumes only 1 cell has separation...

    Steve
    Last edited by Steve Hamley; 7-Jun-2006 at 16:59.

  3. #3

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    Re: Glue Separation?

    Steve,

    I've heard that they had to heat these lenses up at high temperatures in order to separate the elements. Then, they glue them up again.

    Is this true?

    And, one of the risks of the proceedure is that the glass can crack. Is there any substance to this?

    Lastly, I wouldn't think there would be any way possible to predict the rate of separation once it starts, is there?

    I had a "separated" Rodenstock 90 f4.5 back when I first got started in LF. I was told the lens might just as well be tossed into the trash. I did, however, keep the Copal 3 shutter! The cells did go into the recycling bin!

    It sure did hurt to do that! :>|

    Cheers
    Life in the fast lane!

  4. #4
    multi format
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    2,885

    Re: Glue Separation?

    capocheny

    there is info on lens recementing on skgrimes website.
    pretty interesting stuff.

    -john


    Quote Originally Posted by Capocheny
    Steve,

    I've heard that they had to heat these lenses up at high temperatures in order to separate the elements. Then, they glue them up again.

    Is this true?

    And, one of the risks of the proceedure is that the glass can crack. Is there any substance to this?

    Lastly, I wouldn't think there would be any way possible to predict the rate of separation once it starts, is there?

    I had a "separated" Rodenstock 90 f4.5 back when I first got started in LF. I was told the lens might just as well be tossed into the trash. I did, however, keep the Copal 3 shutter! The cells did go into the recycling bin!

    It sure did hurt to do that! :>|

    Cheers

  5. #5

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    Re: Glue Separation?

    It isn't worth regluing a lens like this, get one in good shape. I would NEVER buy one with separation without seeing the issue anyway. I have had 1950's vintage Schneiders with a little snowflake star of separation and it had was to drive down the value of the lens, anything more separation than that I would pass. No, heating will not eliminate the problem, this doesn't fix balsam faults and it certainly isn't going to work with the post-Balsam synthetics.

  6. #6

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    Re: Glue Separation?

    Hi John,

    I've always wondered about the process of repairing a separated lens so I'll definitely take a peek at the link.

    Thank you...

    Cheers.
    Life in the fast lane!

  7. #7

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    Re: Glue Separation?

    S.K. Grimes no longer does the operation, they'll refer you to John Van Stelton at Focal Point. Lenses cemented with Canada balsam are warmed, which is not much of a risk to the lens. Lenses cemented with modern cements are dipped in solvent to dissolve the cement.

    Recoating involves heating the glass, which can crack the glass, but hey, if it's coated it survived once.

    I have a 9-1/2" Gold Dot Dagor that has a tiny amount of separation in the front glass - hardly visible unless you remove the cell from the shutter. I haven't bothered to fix it since stopping the lens down any at all will cover it. It hasn't gotten any worse in the year and a half or so I've had it.

    Steve
    Last edited by Steve Hamley; 7-Jun-2006 at 23:10.

  8. #8

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    Re: Glue Separation?

    On old lenses it is often a matter of balsam seperation---a ring of crusty looking stuff like dried mucilage around the very edges of the lens. It is usually obscured by the aperture blades when the lens is stopped down for picture taking---so no biggie. Turner Reichs for example, often exhibit this malady.

    Of course, this condition isn't going to get any better (given enough time I suppose you wouldn't even have to warm the lens to seperate the elements for A reglue ;-)

    Otoh, you can use it to bargain the price down (waaay down) This is a good thing if you're on a tight budget just so long as you know what you're up against. As a general principle, I don't like messing about with such glass---its doubtful you'll ever be able to get your money out of it and I'm not into the Sally Mann look---there are too many really good old lenses out there to spend your $$ on. Be patient.
    I steal time at 1/125th of a second, so I don't consider my photography to be Fine Art as much as it is petty larceny.

  9. #9

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    Re: Glue Separation?

    Hi Steve,

    Thanks for the info... then that means I should have sent the 90 f4.5 in for re-gluing. I was under the impression that it wasn't worth it and, therefore, it ended up being recycled! Even the manufacturer said it was going to cost more than it was worth at the time! And, that there were no guarantees.

    Such is the learning curve for a newbie at the time!

    So, the risk of the glass applies only for re-coating jobs. Good to know.

    Thank you

    Cheers
    Life in the fast lane!

  10. #10

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    Re: Glue Separation?

    Well, the manufacturer may be right. A used lens in really good shape is worth say 50% of a new one, so you have to assess the $200 against what a good used example would cost - minus the shutter.

    A used Copal 0 or 1 would sell for roughly $150 - $225, and a repair would be $200, so for a typical lens I'd sell the shutter off the funky lens (or use it for something else) and take that off the price of a used replacement. If the replacement minus shutter price is anywhere near $200 just hit the easy button and do the replacement - don't have to wait, risk the lens, ship pieces all over the country...

    If you have a 19" or 24" Gold Dot dagor, that's a different situation altogether.

    Steve

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