Is this lens fungus or just scratching?

Discussion in 'Nikon' started by oskar_ojala, Feb 7, 2010.

  1. I got this Nikon enlarger lens that I noticed on delivery that it has a somewhat weird pattern on the rear element. Now I'm not lens defect expert, so I would ask for your expertise in analyzing this problem. I will post three pictures, one of the rear element at an angle, the second being a crop of the first showing the problem in detail and a third shot directly from behind the lens.
    The pattern consists of a series of disconnected problem areas covering about half of the rear element (outside surface). The problem areas look like cracks, very much like tiny pieces of dust or fabric that comes out of cotton.
    My initial reaction was for some sort of cracks caused by heat or impact, as there are no directional marks suggesting rubbing or abrasion. But I have never seen lens fungus, so I want your honest opinion on this. As a matter of fact, I've never seen anything like this on any of my lenses.
    00Vi0j-218259584.jpg
     
  2. Second image, 100% zoom and crop.
    00Vi0l-218259684.jpg
     
  3. Shot from behind lens (yes those out of focus areas are dust specs apparently).
    00Vi0o-218259884.jpg
     
  4. My vote is FUNGUS. That stight stippling around each fibre, especially on the top of the second shot, rules out benign cloth fibres or some such from cleaning. I've never seen heat do this to a lens coating. Which EL is it?
    I would guess it still works OK, but with reduced contrast maybe.
    AFAIK, there is no cure for fungus short of polishing off all of the coatings and use the lens for imaging in the UV region...
     
  5. Sorry to say, it's fungus. What is worse, picture 2 suggests that it is penetrating into the coating.
     
  6. It's fungus. I have sometimes had luck decreasing the amount of fungus by placing the lens in bright sunlight for several hours on a dry day. It won't repair where the coating is etched, but I have salvaged a few lenses this way
     
  7. penicillin I would guess
     
  8. That is fungus.
     
  9. Thanks for the info. Clearly the lens has been improperly taken care of since the front element has quite obvious cleaning marks and the lens is full of dust. I initially though scratches, but the marks are small for the naked eye and only started thinking after looking close. Now I know better.
    The lens is an El-Nikkor 75/4, a pretty inexpensive lens. I took a few shots with it, the contrast is slightly on the low side, but it's hard to tell what the reason is without a pristine lens to compare to.
    One thing to note is that I cleaned the lens with isopropyl and the marks wouldn't budge, which was a pretty clear indication that there is not going to be any easy way of getting rid of those.
     
  10. Fungus which has been allowed grow to that degree has permanently etched the glass. There is no way to clean it.
     
  11. Fungus definitly,
    I'd get rid of a lens like this asap. and would not put it my on my camera / bellows.
    I know I'm a bit paranoia about fungus, but still ...
    It looks like this fungus in on the outside of the lens-element, and since fungi spread by forming spores which are transported by moving air, they are capable of infecting their environment ( e.g. the camera's or bellows you put the lens on, and through that your other lenses..).
     
  12. It has to be fungus as the unanimous verdict has it.
    You might be able to disassemble the lens and clean and at least kill off the fungus, but the likelihood is that the lens is permanently etched. If, and only if , you can kill the fungus, the lens might still have utility as a soft-focus lens for those dreamy pictorial effects when you print. Fortunately insofar as I have looked, enlarger lenses of good quality are selling for very little these days.
    It's not completely analogous to a rotten apple in the barrel, but the danger of this spreading to other equipment is enough to get this away from everything else. If you still have the option, I'd return it for a refund, depending on how it was described.
     
  13. Definitely the "F" word...but hey, very nice shots of it, especially #2. Very nice indeed.
     

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