Is This Lens Fungus?

Check this out: really educational!

perkeleellinen said:

Hello all,

Is this fungus?

Steve.

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Dear Steve,

You should have a look at this link: astonishing to say the least!

http://www.pentaxforums.com/forums/pentax-slr-lens-discussion/40521-dead-lens-club.html

Here is another!

http://www.deansphotographica.com/deans_of_idaho/old_stuff_pages/dirtylenstest/dirtylenstest.html

Galah - Incredible! I have to say, if I had such a lens, I think I'd be too scared to mount it - it looks like it's alive with fungus.

Just looked at Galah's links and decided I just gots to get me some o' that fungus stuff !!! hat's the thing about fungus..........it GROWS on you !!

Sorry..I just HAD to!!

The results from a fungified 85mm f2 lens on an F100.

It looks just great, mudman, no way of telling the lens has a problem.

It worked just fine, but I had it cleaned anyway, the results were different when the lens flared. You could see the ugly fungi all over the place.

mudman said:

It worked just fine, but I had it cleaned anyway, the results were different when the lens flared. You could see the ugly fungi all over the place.

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Then why go to all the justifications that otherwise the lens takes great photographs? If you cannot take a photograph under some conditions then the lens is useless and needs to be repaired or replaced.

Steve

which is what I did. I never made any other justifications, I just posted a photo I took with the lens. As long as you were aware of what you were shooting, and avoided situations with flare, the lens performed admirably. I never said that the lens was completely stellar no telling that there was anything wrong with it. Just that 90% it didn't matter that there was fungus in it.

I know from balancing the exposures of 9-up and 16-up lensboards for package printers that you can put something opaque, like model airplane dope, on a lens and still get a perfectly acceptable print. The dot of fluid dries and behaves in much the same way as a secondary mirror in a catadioptric system, which is to say you get donut-shaped out-of-focus areas and you lose a little light and contrast. Fungus should do more or less the same thing unless it's really bad.

About ten years ago, I gave a Tamron 70-210/3.5 that I wasn't using to a friend from college. She stopped using it and it got stored in god-knows-what conditions for several years. I got it back last November when she was cleaning out her packing after moving. The lens was covered in fungus, inside and out, with maybe four or five internal surfaces affected; it had very low contrast overall, much lower than when I used it regularly. It was still usable unless you put it in a situation where it would flare, in which case it was horrible. I think it depends on how much fungus there is, and where it is, along with the lighting in the image and how much you stop down (large apertures being better due to DOF, I suppose; I didn't really try any sort of scientific experiment to figure it out, because I have a Nikon Series E 70-210/4.0 that is a better lens IMHO).

I was told that fungus developped especially in hot climatic conditions (Mediterranean, tropics, etc).
Glue can also deteriorate and create problems on glass surfaces.
Whatever it is, don't hesitate a minute to report it to the seller. They should have checked carefully the lens before putting it on sale and mentionned this in their advert.