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Thread: Can you help me get this lens cell apart

  1. #1

    Join Date
    May 2016
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    Licking County, Ohio
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    Can you help me get this lens cell apart

    I bought a Bausch and Lomb Tessar Ic today that I hope turns out to be a good deal in the end. The lens was hazy but my experience with previous B&L Tessars is that I could easily open them and clean the haze away. The rear cell thankfully turned out to only have haze on the outside surfaces. The front cell, sadly has haze on the internal surfaces too and I can't figure out how to get the damned thing open. The front lens is slightly loose/rattly and it looks like the crenelated ring with the inscribed lens info should screw out of the barrel but it won't budge. Any ideas on what to do?


    Crappy cell phone pic of the victim:


  2. #2

    Join Date
    May 2006
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    Scarsdale, NY
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    328

    Re: Can you help me get this lens cell apart

    There's always a hint - see the knurling on the top of the piece holding the beauty ring in? Get yourself a big rubber stopper or something else to get some friction on that ring and start turning. There are marks in the knurling at 10 and 1 o'clock. I can't tell if they're notches for a lens wrench or not. Check it out. If there are notches at 180 degrees, you've got your answer.

    Charley

  3. #3

    Join Date
    May 2016
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    Licking County, Ohio
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    335

    Re: Can you help me get this lens cell apart

    I have been trying with the rubber "lens wrench" cones and no luck. I'm twisting the hell out of it but the cone eventually just squeaks across the metal ring. I think the deeper marks in the crenelations are damage, not notches for a wrench but I'll inspect it to see if there's an opposing pair.

    I'm freezing it now to see if it'll come loose in the morning. I had a cell stuck in a shutter once that released easily once frozen.

  4. #4

    Join Date
    Oct 2013
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    Bow, NH
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    Re: Can you help me get this lens cell apart

    The Tessar lens design show that the front group is made up of two air separated lens elements. Have you tried unscrewing from the back of the front lens group to get at the internal surfaces?

  5. #5

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    Re: Can you help me get this lens cell apart

    Quote Originally Posted by djdister View Post
    The Tessar lens design show that the front group is made up of two air separated lens elements. Have you tried unscrewing from the back of the front lens group to get at the internal surfaces?
    In my older B&L Tessar, that's exactly how it opens up and how I was able to clean the haze out of it. This newer one is constructed differently. The barrel is a single piece from front to back. Nothing wants to screw off, which is why I'm assuming that the front inner ring screws out. Though so far that assumption is failing me.

  6. #6

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    Re: Can you help me get this lens cell apart

    Can you snap a picture of the back of the front lens group?

  7. #7

    Join Date
    Dec 2001
    Location
    San Joaquin Valley, California
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    8,958

    Re: Can you help me get this lens cell apart

    I've used a rubber strap wrench with good results in situations like yours. Try the $1.99 cent table at Ace or (as much as I hate to say it) Harbor Freight
    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.
    I'm not OCD. I'm CDO which is alphabetically correct.

  8. #8

    Join Date
    Jan 2009
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    Denmark
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    Re: Can you help me get this lens cell apart

    This is an unfortunate back entry job.
    The two lenses and spacer have been loaded from the rear and the brass tube has been lathe burnished (Friction causing the brass to become plastic)to create a thin retaining overlap.
    This system was cheaper in terms of labour costs than making threads and screw rings. The lenses were never expected to be in use more than a dozen years, or so!

  9. #9

    Join Date
    May 2015
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    SooooCal/LA USA
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    Re: Can you help me get this lens cell apart

    Let's see a pix of the back c/u, but maybe what Steven said...

    Others that I have cleaned unscrew the retainer for the thicker 2nd element and once removed, you can access the 1st element rear surface...

    I have seen a description of how to undo a burnished rear seat, as it is thin, but don't remember where, but possible...

    These cloud over in time as barometric pressure seeps in a little moisture, that leaves some calcium deposits when the moisture can't leave...

    Steve K

  10. #10

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    Re: Can you help me get this lens cell apart

    Quote Originally Posted by LabRat View Post
    Let's see a pix of the back c/u, but maybe what Steven said...

    ....

    I have seen a description of how to undo a burnished rear seat, as it is thin, but don't remember where,....

    Steve K
    I am sure I have submitted a description here in connection with RR cells or Pezval achromat. There is an almost a certain garantee that parts of the turned-back edge will break off - but the glass will be OK!

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