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Kanirasta
Tinkerer
Username: Kanirasta
Post Number: 1
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, July 12, 2009 - 10:10 am: | 
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I have one Canonet QL17 that I got incredible cheap because it wasn't working and the lens had fungus.
I managed to open it and make it work (my first try at camera repair). But I also wanted to solve the fungus problem, so I tried to clean it with Stop Bath (which is Acetic Acid or so I 've been told).
The fungus didn't clear, so I left the elements submerged in the liquid for a day.
The problem is some elements are just like they were (fungus and all) but the front element is VERY cloudy, just like ground glass. You almost can't see through it. It was the worse infected but it still rings strange that the remainding elements had no problem with the acid and this did?
Or maybe it is that the fungus changed state now clouding the lens?
Was it a mistake to submerge the elements on acetic acid? |
Casual_collector
Tinkerer
Username: Casual_collector
Post Number: 15
Registered: 04-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, July 12, 2009 - 05:07 pm: |
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Glass and acid seem to get along OK. I'm not so sure about magnesium flouride (lens coating) and acid. |
Glenn
Tinkerer
Username: Glenn
Post Number: 626
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, July 12, 2009 - 05:35 pm: |
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Judging by the results, the answer to your last question is yes. Whilst many people advocate the use of vinegar when dealing with fungus, acid stop bath is a completely different kettle of fish. At working strength (2%) a slight soak and wipe will do no harm, the results being similar to that if vinegar (typically 5%- 10% acid conc) was used. However; acid stop bath is typically 28% acid prior to dilution to working strength, soaking in the concentrate for any extended length of time is likely to damage some types of lens coating. I suspect you now have a good example of an acid etched front element, if you used the concentrate. |
Kanirasta
Tinkerer
Username: Kanirasta
Post Number: 2
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, July 13, 2009 - 05:07 pm: |
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I used the diluted solution I use to develop. It's not concentrate.
What seems strange is that the other elements were unharmed and also, the one that cloudiness seems to be at the back of the first element not the front. I don't know I thought that maybe it was the same fungus that caused the issue, not the acid. But I'll take that it was the acid.
Thanks! |
Casual_collector
Tinkerer
Username: Casual_collector
Post Number: 16
Registered: 04-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, July 13, 2009 - 05:36 pm: |
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If that element is a cemented pair, perhaps the acid attacked the cement. |
Mike_kovacs
Tinkerer
Username: Mike_kovacs
Post Number: 18
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 23, 2009 - 11:20 am: |
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Acid will dissolve lens coatings. In fact it is lactic acid from anaerobic fungus that etches the coatings so effectively.
Bad move! |
John_s
Tinkerer
Username: John_s
Post Number: 2
Registered: 07-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 23, 2009 - 01:20 pm: |
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Your only hope might be to remove the coating altogether by somehow polishing it off. I have used toothpaste, which is very mildly abrasive, to do this without obviously causing damage to the glass itself. |
