Fungus

Discussion in '35mm Cameras and Accessories' started by BobbyR, Dec 4, 2007.

  1. BobbyR

    BobbyR Member

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    How expensive is it to fix a Nikon auto focus lens with fungus?
     
  2. Dan Fromm

    Dan Fromm Member

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    Ask Nikon or a Nikon service shop. And when you ask them, tell them which lens you're asking about.
     
  3. David H. Bebbington

    David H. Bebbington Inactive

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    As a rough guide, fungus can be fixed completely only when it is at the "dust speckle" stage. Once it has progressed to looking like ice crystals, a complete cure would involve dismantling the lens in question, cleaning off the fungus, repolishing and recoating the pitted glass surfaces and re-assembly with collimation. In almost all cases, all this work would cost (far) more than the lens is worth.
     
  4. John Koehrer

    John Koehrer Subscriber

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    David is correct In Theory. From a practical standpoint though, Depending on the lens it's a matter of cleaning & reassembly. The precision involved in manufacturing the assemblies takes much of the slop out of reassembling a lens made in the last 30-40 years. If you've put the thing together in the correct sequence it's gonna work & collimating the lens will make no difference in picture quality. For technical photography possibly, general work---nada----- nothing you're going to see.
     
  5. Dan Fromm

    Dan Fromm Member

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    Which 35-70 AF zoom? f/3.3-4.5? f/2.8? Don't be so coy, tell us everything including how much fungus and where. If the f/3.3-4.5, $100 is too much for a good one; you can get a good one from KEH for ~ $50. If the f/2.8, maybe but you still probably shouldn't.
     
  6. BobbyR

    BobbyR Member

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    OK here is the bottom line, would any of you buy a Nikon 35-70 f2.8 AF zoom, for less than a hundred dollars, hoping repair would not make is not a deal?---"The glass has haze on the internal elements. This may have a softening affect on image quality."
    Bobby

    PS--I checked KEH, and I guess I am stuck (I do NOT absolutely need this lens) between taking a gamble or waiting if I do need one, to simply go to a store and get one that is fine with a warranty.
     
  7. Dan Fromm

    Dan Fromm Member

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    If you don't need the lens, remember the most common bit of advice in Monty Python & The Holy Grail. Run away! Run away!

    Haze isn't fungus. Fungus isn't haze.

    Haze isn't fungus. Fungus isn't haze.

    "This may have a softening effect on image quality" means that you can count on the lens to pass light and form an image and that's all.

    Run away! Run away!
     
  8. copake_ham

    copake_ham Inactive

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    Bobby,

    It's hard to answer your question without knowing your risk tolerance. If a price under a C-note is not a financial burden to you - it might be worth the gamble.

    I have a 35-70/2.8 and it's a very nice lens.

    The seller is being honest with you - and may also be a bit naive. Where is the seller located? If she/he's in a humid climate you may have a situation where there is embedded moisture in the lens creating the hazing effect.

    Drying it out may be all it needs if you are in a drier climate.

    ------------------------

    Dan,

    You speak with some authority about the haze not being fungus.

    What would be your thinking as to what is causing the haze?
     
  9. BobbyR

    BobbyR Member

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    Thank you gents; my gut instinct said no and your answers pretty much tell me there are are fish in the pond.
    Thanks again,
    Bobby
     
  10. David H. Bebbington

    David H. Bebbington Inactive

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    Not to tread on Dan's toes, but as I understand it, almost all zoom lenses change focal length by moving a central lens group back and forth. This means that the volume of the internal air spaces within the lens change and in turn means that a lens has to have some small breather holes (otherwise you couldn't work the zoom). This opens the way for air to enter the lens. If this air is humid, haze may form. If it is dirty (tobacco smoke, etc.), the haze may be more persistent and will not disappear when the lens is warmed up. Mold spores are I believe frequently present in the air, if they enter the lens through the breather holes and are then left in warm humid conditions, mold growth will result.

    I try to combat mold by not buying second-hand lenses with any visible speckles inside, by storing lenses in cases or plastic bags with silica gel sachets, and by drying gear carefully if it has been out in damp conditions. Many times I ahve driven home from a landscape shoot with the car heater up full and the camera bag open on the passenger seat. In poor conditions I usually carry a towel and wrap the camera in the towel immediately if any water drops fall onto it.

    Regards,

    David
     
  11. copake_ham

    copake_ham Inactive

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    David,

    Thanks. While we should also let Dan respond, your advice seems "spot on".

    The "smoker" thing would seem to be much more problemattic than humidity and, given the likely age of the lens and the prevelance of smoking back then - is really good cautionary advice.

    I'll certainly keep it in mind if/when I'm fishing around for used zooms.
     
  12. Dan Fromm

    Dan Fromm Member

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    George, David answered your question pretty well but didn't mention lubricants. Some of the lubricants used in focusing helicals and leaf shutters will outgas when warm and what comes out can condense on the glasses. Aged LF lenses often suffer from this kind of haze. Unlike the zoom lens that BobbyR was thinking about, many LF lenses come apart easily for cleaning.

    Cheers,

    Dan