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05-11-2011, 11:18 AM   #1
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How does this happen?

Hi All,
What causes fungus to start growing on a lens?

05-11-2011, 11:27 AM   #2
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Maybe this is worth reading...Know Your Lens Fungus
05-11-2011, 02:19 PM   #3
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A dark, moisture-rich environment (including just being in a humid/tropical climate). Remember, there is always fungus among us.

So, lenses stored with caps on in a camera bag = good place to grow fungus.
05-11-2011, 02:29 PM   #4
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Lenses kept in a dark, dry, cool place = less likely to grow fungus.

05-11-2011, 07:10 PM   #5
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Demons summoned by evil lensmakers in obscene rituals cause fungal infestations, forcing poor suffering users to buy new lenses. It's all a nefarious plot. The only cure is an exorcism followed by repeated chanting of a good mantra. This one always works for me:
Owa
Tagu
Siam
Repeat forever.
05-11-2011, 07:43 PM   #6
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QuoteOriginally posted by RioRico Quote
Demons summoned by evil lensmakers in obscene rituals cause fungal infestations, forcing poor suffering users to buy new lenses. It's all a nefarious plot. The only cure is an exorcism followed by repeated chanting of a good mantra. This one always works for me:
Owa
Tagu
Siam
Repeat forever.
Good Humor! I remember my father getting me with this one quite a number of years ago. Tried to get my 8-yr old to fall for it a week or so ago but no joy...
05-11-2011, 08:20 PM   #7
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I get the dry, cool, but I thought dark was a contributing factor to fungus growth. Maybe because a "cure" was told to me as taking off the caps and sitting in a directly sunlit place so that the UV can kill the fungus. Wrong? Wright? sorta?
05-11-2011, 09:15 PM   #8
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I actually got the Ultraviolet imaging department at local university to fire a 266 nm 1Kw laser through Takumar 50mm f/1.4 lens that had a bad case of fungus and the dreaded yellowing (this one was really bad) and in 0.8 seconds it was crystal clear and the fungus flaked off when I disassembled it.


Last edited by Digitalis; 05-12-2011 at 01:38 AM.
05-11-2011, 10:17 PM   #9
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C'mon. I totally disbelieve.

How do you count to 0.8 sec anyway? Is it have to do with currency conversion?
05-12-2011, 01:23 AM   #10
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QuoteOriginally posted by John Araki Quote
How do you count to 0.8 sec anyway?
This was an experiment I have wanted to do for some time, and I know quite a few people at the science department at Adelaide University who were also interested in this particular problem. the takumar lens was given to me because of the damage from the yellowing and the fungus.

The YAG laser was pulsed and had it's power output reduced. Ordinarily solid state YAG lasers in the Kilowatt energy class are only capable of exposing a target for only a few nanoseconds, but at a reduced power level the laser was able to sustain a relatively longer exposure equivalent to a continuous exposure of 750w for 0.8th of a second. This length of time was needed due to the high absorption of UV light by the glass in the lens. The absorption of the energetic UV photons increased the temperature within the lens further aiding the elimination of the fungus.

Damage to DNA occurs in the presence of UV light in the 254~266nm range, several enzymes become denatured and in the presence of 186nm UV light DNA is able to be effectively destroyed. But unfortunately to use 186nm UV would have been impractical because the lens would have to have been stripped down and placed in hard vacuum due to the fact that air becomes opaque those wavelengths.

Last edited by Digitalis; 05-12-2011 at 01:39 AM.
05-12-2011, 07:44 AM   #11
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QuoteOriginally posted by K57XR Quote
Maybe this is worth reading...Know Your Lens Fungus
Thanks for the link. Very good info.
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