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Thread: Cooke Series II 12.75" Anastigmat - Disassembly, Stuck Focus Ring

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    Unwitting Thread Killer Ari's Avatar
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    Cooke Series II 12.75" Anastigmat - Disassembly, Stuck Focus Ring

    Not much information on the internet - a little, but not enough, so I thought I'd ask here.
    I have a Cooke knuckler, a 12.75" f/4.5 Series II lens, looks exactly like this one (minus the shine):

    Click image for larger version. 

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    The soft-focus ring, actuated by using the "knuckles" is stuck. But really stuck.
    I need some more leverage, and in order to get that, the middle element needs to be removed so that I don't damage it.
    I just don't know how.

    Online reports say this element is cemented in there for good. Others say it's cemented but can be removed by soaking in the right solvents.

    Does anyone know how to remove the middle element?

    Thanks in advance.

  2. #2

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    Re: Cooke Series II 12.75" Anastigmat - Disassembly, Stuck Focus Ring

    Old lubes can turn tar-like... Sometimes a stuck ring etc can be freed by a repeat application of lighter fluid, alcohol, acetone, silicone spray (containing acetone) applied with a hypo syringe in microdrops, then waiting awhile before another micro application, but you have to survey what is around that area that can be affected by the solvents (paints, iris blade materials, lens cements etc)... Maybe a little heat from a hair dryer to warm parts etc...

    But the process depends on what's needed in your case, so be wise or send it out to an expert...

    Steve K

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    Re: Cooke Series II 12.75" Anastigmat - Disassembly, Stuck Focus Ring

    Thanks, Steve. I have an expert looking at it right now, so it's safely out of my hands.
    The middle lens removal had me stumped when I tried, and I wanted to know if anyone succeeded in removing it, and then putting it back successfully.

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    Re: Cooke Series II 12.75" Anastigmat - Disassembly, Stuck Focus Ring


  5. #5
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    Re: Cooke Series II 12.75" Anastigmat - Disassembly, Stuck Focus Ring

    Thank you, Steven. Very helpful.

    Has anyone successfully removed the middle element, if so, how was it done?

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