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Discussion in 'Lens Matters' started by transition, Sep 27, 2017.

  1. transition

    transition Member

    Sorry, I'll introduce my interest.
    I have owned cameras for 60 years. I am not a photographer but I take pictures. I like to own nice equipment whether it is functional or not.
    At the present time my interest is in owning Nikon film cameras and lenses. I frequent ebay and occasionally I'll actually bid for something (usually) cheap.
    Some would argue I'm a collector not a photographer. However, I do take photographs though the end result leaves a good deal to be desired. That is where I derive my interest in photography and why I joined this forum so I hope members will not be upset by my honesty.
    I see a term "fungus" usually on the inside of a lens.
    How detrimental is fungus to a lens please? Is it possible to clean out?
    How difficult is it to dismantle a lens and is it actually worth the risk?
    Thank you,.
  2. PeteRob

    PeteRob Well-Known Member

    Very detrimental. If it has got hold then the lens is generally ruined. UV light can kill fungus but do quarantine any affected lens because it can spread. If using sunlight as a UV source be careful to not set a fire. Taking a lens apart is easier than putting it together again with everything aligned but if you do have a damaged lens you can play away and perhaps repolish the affected surfaces. I don't know what test equipment you need to assure the elements are properly aligned.
  3. transition

    transition Member

    Further to my request for information. Another thing I see frequently when viewing lens descriptions is reference to oil on the aperture. Where does this oil emanate from please and is it detrimental to the lenses operation?
    Thank you again.
  4. Roger_Provins

    Roger_Provins Well-Known Member

    Oil on the diaphragm blades is usually caused by minute amounts from the grease on focusing gears seeping to where it shouldn't be. Causes the blades of the diaphragm to partially stick together and either jam completely or slow down. The only solution is a complete lens strip down and clean.
  5. PeteRob

    PeteRob Well-Known Member

    I've never heard of it but I am not a collector. The aperture is controlled by several blades that overlap. I guess these are lubricated but I'd expect a dry lubricant rather than oil or grease which would pick up dirt in time leading to the blades sticking. Similarly, lens internal movements must have some kind of lubricant, probably a touch of relatively high melting point grease so it doesn't run everywhere under normal temperature conditions. It is possible that lenses need to be specially prepared for use in temperatures > 40 C as found in some countries and conversely for operation at temperatures < -10 C.
  6. Roger Hicks

    Roger Hicks Well-Known Member

    Dear Pete,

    The fungi that attack lenses are everywhere in the house and can infect a previously untouched lens as easily as re-infecting old ones. There is absolutely no need for quarantine.


  7. Roger Hicks

    Roger Hicks Well-Known Member

    As usual, the answer is a firm, unequivocal "it depends". Left for long enough, fungus can etch a lens, but until then, it can just be wiped off IF you are competent to strip and reassemble a lens. With some lenses, partial stripping is easy, so you can remove maybe the front and rear group. With others, and stripping is difficult or impossible. Go onto specialist forums or sub-forums for information on specific lenses.

    Fungus will reduce contrast and (to a far smaller extent than seems probable) resolution.

    As for oily diaphragms, some were indeed lubricated with oils either when new or when repaired. Again it'll be a question of specific lenses. Not Nikon, but I had a 50/1.2 Canon stripped, cleaned and overhauled (by a company now out of business) and was delighted with the result.

    If your pictures are indifferent anyway, ask yourself how much they are likely to be affected by reduced contrast, oily blades, etc..



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