Canon lenses: iris stuck wide open

Discussion in 'Canon' started by Bob Niland, Aug 7, 2003.

  1. Bob Niland

    Bob Niland Guest

    I just pulled my 35mm gear out of storage,
    and two of the first 4 FD lenses I checked
    have their irises stuck at full aperture.
    I'm checking this both in stop-down-AE
    mode and with some reversing accessories.

    Is there any chance this problem will
    correct itself if I mount a stuck lens,
    set it to min-ap in stop-down mode, and
    just leave it for a few days?

    Or does this require disassembly of the
    lens? If so, any estimates on typical cost?
    --
    Regards, PO Box 248
    Bob Niland Enterprise
    mailto: Kansas
    which, due to spam, is: 67441-0248 USA
    email4rjn AT yahoo DOT com
    http://www.access-one.com/rjn

    Unless otherwise specifically stated, expressing personal
    opinions and NOT speaking for any employer, client or Internet
    Service Provider.
     
    Bob Niland, Aug 7, 2003
    #1
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  2. Bob Niland

    Mike Guest

    Making the assumption that the remainder of the lens is working correctly I
    would
    suggest there is oil from the helicoid grease on the diaphragm blades.
    Cost of repair will depend on who does the work, some where between $40 and
    $70.00. The blades will need to be removed for cleaning.
    Mike
     
    Mike, Aug 7, 2003
    #2
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  3. Bob Niland

    Bob Niland Guest

    ... I would suggest there is oil from the
    I tore the NewFD 135mm f4 down far enough
    to wiggle the actuators, and managed to
    free up the diaphragm.

    Sure enough, there's heavy oil or thin grease
    on the blades. Even though the lens is sorta
    working now, I'll bet the blade response is
    too slow to be fully stopped-down when the
    shutter fires.

    I'm not inclined to attempt further dissection,
    so I'll probably just make the two stuck lenses
    "as-is" bonus items, with full problem details,
    on some related photo gear I'm about to auction.

    Is this a design flaw in Canon lenses? Or is it
    a function of orientation, and possibly temperature
    fluctuation and pressure fluctuation in long-term
    storage? If the latter, seems like there needs to
    be a recommendation for storage orientation.

    Thanks for the responses.

    --
    Regards, PO Box 248
    Bob Niland Enterprise
    mailto: Kansas
    which, due to spam, is: 67441-0248 USA
    email4rjn AT yahoo DOT com
    http://www.access-one.com/rjn

    Unless otherwise specifically stated, expressing personal
    opinions and NOT speaking for any employer, client or Internet
    Service Provider.
     
    Bob Niland, Aug 10, 2003
    #3
  4. More likely it is just the result of some greenhorn on the assembly line who
    doesn't know what he's doing.....Certainly it isn't just a problem with
    Canon.....I've seen a few Nikkors with sticky diaphrams too.....Oil and
    grease get dry with age, and when dry, they thicken up. - This is more
    likely to happen with a lens that has been sitting unused for a long
    time......It's good to work the diaphram by pressing the little cam follower
    on the back of the lens a few times now and then.....Whenever you inspect
    your lenses for fungus or whatever.......
     
    William Graham, Aug 10, 2003
    #4
  5. Bob Niland

    Mike Guest

    Oil is deposited on the diaphragm blades when the grease breaks down due to
    age or temperature. The best way to remove the oil is to remove and clean
    not only the blades but the entire assembly. The blades are ment to run dry
    and without grease or oil.
     
    Mike, Aug 10, 2003
    #5
  6. Bob Niland

    Slingblade Guest

    To my knowledge, Canon never made a New FD 135mm f4 (or for that
    matter a breechlock model either).

    The f3.5 was the smallest max. aperture model for a prime 135mm in the
    New FD line.
     
    Slingblade, Aug 10, 2003
    #6
  7. Bob Niland

    Bob Niland Guest

    I tore the NewFD 135mm f4 down far enough
    Yep. It's a 3.5.
    Midnight posting strikes again.
     
    Bob Niland, Aug 10, 2003
    #7
  8. ....
    Pop it in a vapour degreaser, or ultra sonic cleaner with solvent and
    remove ALL the grease. Go see your local Leitz/Zeus what ever
    instrument suplier and get a non-mobile no sublimation grease and use
    that. The grease may cost you $20-30 a gram, but you only need a few
    mG. A 6B pencil is good for the iris, and cleaned than loose graphite.


    --
    Paul Repacholi 1 Crescent Rd.,
    +61 (08) 9257-1001 Kalamunda.
    West Australia 6076
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    Paul Repacholi, Aug 10, 2003
    #8
  9. Thanks, Paul. Good info.

    Victor
     
    Victor Bazarov, Aug 11, 2003
    #9
  10. Bob Niland

    Bob Niland Guest

    Is this a design flaw in Canon lenses?
    As I see from a recent report of an FD Vivitar
    (Kiron) with the same problem. I'm going to need
    to double-check my "good" lenses before selling
    them.
    I wish. In addition to the 35-105 and 135 with
    stuck or sluggish diaphragms, I just discovered
    that my 24mm/f2.8 also has a sloggy winker ...

    .... AND there's this little spectrally-refracting
    spot on the inner surface of the front element.
    Looks just like a tiny drop of oil spread out.

    I'm going to list all three cans as-is on eBay in a
    couple of weeks, with full descriptions about what
    I figure the problems are. The auction might fetch
    more for the zoom's 72mm attachments than for the
    lenses themselves.

    "Warranted to be defective. Refunds cheerfully
    given if this is found to be not the case :)"

    --
    Regards, PO Box 248
    Bob Niland Enterprise
    mailto: Kansas
    which, due to spam, is: 67441-0248 USA
    email4rjn AT yahoo DOT com
    http://www.access-one.com/rjn

    Unless otherwise specifically stated, expressing personal
    opinions and NOT speaking for any employer, client or Internet
    Service Provider.
     
    Bob Niland, Aug 12, 2003
    #10
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