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Aphototaker
Tinkerer
Username: Aphototaker
Post Number: 49
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 05, 2010 - 12:52 pm: | 
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Hello,
I have cleaned fungus off a few spots on one my lenses. It was a zoom lens that I seldom used and was always stored in my camera bag. Both factors, I am assuming, contributed to the few spots of fungus on the back of its front element.
Anyhow, I cleaned it off by opening the lens and wiping the fungus off with an ear bud doused in hydrogen peroxide (available from any pharmacy) mixed with ammonia (bleaching agent, from any pharmacy).
The fungus was actually that typical spider-web like thing at three areas on the lens surface. One spot had a diameter of around 5 mm, the others were around 2~3mm. All three had a center spot from which the thread-like stuff seemed to have originated, that spot being a small dot of hardly 0.5 mm wide.
When I cleaned off these three spots, I noticed that the solution was sticking to the spot covered by the fungus in each case, unlike on the rest of the glass where the solution was moving around without sticking to it. I also noticed that as I tried to wipe the fungus areas with a lens tissue gently, I could feel distinct friction on those spots. The tissue moved freely on the unaffected lens surface. And if I were to scrub it a bit harder on the affected spots, I could see I was able to scratch some relatively soft hard-gel like thin layer over there.
I noticed this by doing the experiments on a pot near the periphery of the lens.
Does all this sound familiar? Does the fact that the solution was sticking to the affected spots signify destruction of lens coating there? What is the thing which I can scratch, which appears to be relatively soft (like dried jam, for lack of better analogy) at the affected areas after the fungus has been removed?
Thanks. |
David_nebenzahl
Tinkerer
Username: David_nebenzahl
Post Number: 123
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 05, 2010 - 01:43 pm: |
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Not sure about that soft substance you seem to be finding, but I do know that fungus can actually attack glass and lens coatings, probably because of an acidic (or alkaline) secretion that attacks the lens, which is why you may not be able to remove traces of the fungus, even if you can remove the fungus itself. |
Aphototaker
Tinkerer
Username: Aphototaker
Post Number: 50
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 05, 2010 - 02:40 pm: |
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I think I should not call that different texture a "substance". It is just a different feeling when I rub over that area than the rest of the unaffected glass.
I was hoping that people who have more experience with fungus cleaning would be able to recall similar feeling and perhaps validate or confirm what I had observed. |
M_currie
Tinkerer
Username: M_currie
Post Number: 212
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 07, 2010 - 08:09 am: |
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As I understand it, at least some fungi actually etch the glass or the coating. If that's the case you'll always have a mark even if you effectively kill the fungus.
Here's one site that seems to be pretty informative:
http://www.mypentax.com/Fungus.html |
Aphototaker
Tinkerer
Username: Aphototaker
Post Number: 51
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 07, 2010 - 09:42 pm: |
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I took another take on some fungus. This is the same zoom lens whose front element I had cleaned earlier. This time, there was this very tiny spot of fungus on the inner rear element.
Opening up the lens and reaching that element was a monumental task by itself. But I have noticed that using a cotton swab dipped in hydrogen peroxide and ammonia solution once is not enough to wipe off the fungus.
What appears to be happening is that the cycle of wipe with ear bud doused in the H2O2 and NH3 solution and then drying it out needs to be repeated a number of times. I had to do this five or so times to get any remnants of the tiny amount of fungus off. If the procedure is not repeated sufficient number of times, the remnants of fungus appear to be felt like the smoothness with different friction than the good glass that I described above.
After I had gone through the iterations five or so times, I could feel the smoothness of the glass the same all over it, and the solution was also not sticking to the glass anymore as it was on the infected region before.
In short, the difference kind of smoothness that I described at the place of the fungus infection appears to be just the fungus itself that is still there and needs to be cleaned with the ammonia and hydrogen peroxide solution for multiple iterations till the fungus is all removed.
Regards. |
Lorriman
Tinkerer
Username: Lorriman
Post Number: 21
Registered: 06-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 08, 2010 - 09:35 am: |
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The official recipe from one of the lens manufacturers includes distilled/de-ionised water along with ammonia and hydrogen eroxid which has its own caustic nature that may be helpful in preventing reoccurance. It also has to be left for an hour. |
Fallisphoto
Tinkerer
Username: Fallisphoto
Post Number: 108
Registered: 09-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 13, 2010 - 10:49 am: |
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No, a quick wipe isn't enough. I don't think anyone ever suggested it would be. I soak the stuff about 4 hours in it, THEN wipe it off. |
