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Thread: How to fix frozen iris in a Cooke Portrait Soft Focus Series II 8x10 13"?

  1. #11

    Join Date
    Mar 2004
    Posts
    645

    Re: How to fix frozen iris in a Cooke Portrait Soft Focus Series II 8x10 13"?

    Do unscrewing over a tray, as this sized screw becomes invisable in seconds.

    I would suggest lining the tray with a light-colored towel. Small screws can bounce surprisingly well, and are sometimes hard to pick up.

    (Has anyone but me ever had an aperture scale screw from a Copal shutter get loose in the kitchen?)

  2. #12

    Join Date
    Dec 2000
    Location
    Tonopah, Nevada, USA
    Posts
    6,338

    Re: How to fix frozen iris in a Cooke Portrait Soft Focus Series II 8x10 13"?

    Before you give up and mail it to USA. I use this stuff. It is an automotive product used for cleaning tire repairs. It has heptane, hexane and acetone and is not particularly environmentally friendly. BUT it leaves no residue and has proven safe even on the oldest non metal aperture blades. It will positively flow into threaded areas and clean out the gunk. Sometimes it takes more than one "service". It will operate freely, but when the solvent dries up it freezes again. Repeated times will finally get the gunk to flow out. Gunk can be a residue, so cotton cloths and "Q tips" are required to lift gunk away as it dislodges. Maybe Europe has a similar product? If you find something similar you can look at MSDS sheets to see if it has the same chemical agents.

    The old product had trichloroethylene. Even more dangerous. The replacement stuff seems to work just as well. I've been using this stuff for years. Also works well to dislodge gunk from shutter mechanisms. Again leaves no residue, but washes out gunk that IS a residue if not lifted out with swabs and cotton, or sometimes a tiny bid of air pressure.

    The machined surfaces on the Cooke lenses are spectacularly tiny. It doesn't take much gook to make them stall.

  3. #13

    Join Date
    Nov 2012
    Location
    Paris, France
    Posts
    41

    Re: How to fix frozen iris in a Cooke Portrait Soft Focus Series II 8x10 13"?

    Thank you Jim, gonna try to find this stuff.
    For now, I've tried with "essence F" (in french, I guess it's similar fluid lighter) and few drops of acetone, bot nothing appears

  4. #14

    Join Date
    Jan 2009
    Location
    Denmark
    Posts
    5,932

    Re: How to fix frozen iris in a Cooke Portrait Soft Focus Series II 8x10 13"?

    As you might have guessed, Jim's suggestion can only be used outdoors. And it will attack any lacquer it comes into contact with - even for a second or so.

  5. #15

    Join Date
    Dec 2000
    Location
    Tonopah, Nevada, USA
    Posts
    6,338

    Re: How to fix frozen iris in a Cooke Portrait Soft Focus Series II 8x10 13"?

    Quote Originally Posted by Steven Tribe View Post
    As you might have guessed, Jim's suggestion can only be used outdoors. And it will attack any lacquer it comes into contact with - even for a second or so.
    I always use indoors. It has never ever attacked any painted surface.

  6. #16

    Join Date
    Nov 2012
    Location
    Paris, France
    Posts
    41

    Re: How to fix frozen iris in a Cooke Portrait Soft Focus Series II 8x10 13"?

    Some news, I've found the magical stuff Jim had suggested in a local tyre repairshop ( a charming man, gave me some product in a small bottle to try), but after three test, it doesn't work. So this lens was shipped to state of Rhode Island this morning...
    Thank you all for your help

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