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Adrian
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 27, 2005 - 10:12 am: | 
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Having managed to restore a dead Werra 3 to some semblance of working order (big bouquet to a CCRF member - you know who you are!), I now fancy a go at the lens on its stablemate. This is a Werra 1 with the ordinary Tessar lens. It has a small colony of fungus that looks to be on the back of the front element, and the rear element has a most impressive growth across it as well.
I have nothing to lose (except screws, small pieces etc) by trying to remove the fungus, and I'd be interested to hear if anyone else has done so. I realise that I may find the lens is knackered underneath it, I'm not rushing madly in in the hope of finding a perfect lens underneath.
As I work in a lab I can get hold of chemicals etc (I've heard about cold cream, but I can't imagine it killing fungal spores), but I just wonder about concentrations to use and so on.
Thanks for the help,
Adrian |
charlie
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 27, 2005 - 10:49 am: |
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I have read in several threads that ultraviolet light will kill fungus. You put the lens in a place where sunlight will shine through elements. Not everyone agrees as to its effectivity and I have never had a need to try it but it seems to be the least invasive method and may be a good first attempt. I think if you could put the lens in direct sunlight (not behind a window) it might work quicker. Let us all know. |
Henry
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 27, 2005 - 02:10 pm: |
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Although sunlight will KILL fungus, it will NOT REMOVE it. You'll need to disassemble then clean it off manually. Just check the archives...do a search on fungus...and you'll find lots of info.
Henry |
paul ron
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 27, 2005 - 07:41 pm: |
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Why don't you ask a mycologest in your lab? Perhaps an anti fungal cream, I have never seen anyone do it nor have I tried it but it sounds like a solid solution, it just might work. You have nothing to loose except an investment in tube of athlete's foot cream. |
zygiozi
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 28, 2005 - 03:58 am: |
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Hi.My humble advice from my experience with old lenses; use apple cider (special vinegar) Works mint! Kills bacteria and refreshes glass. Quarranteed. If the lense is glued ( two part stuck in one element )you have to put it to hot water to separate them and after clean put them together glued by gelly.Zygi |
Winfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 28, 2005 - 04:21 am: |
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Especially on post-war east german lenses I never had any problems with the vinegar affecting the lens coating. It seems they used a rather hard coating for its age.
In most cases the fungus does not affect the lens cement in cemented groups so you probably don't have to disassemble a lens group. Just clean every surface and reassemble.
I have seen that on at least some of the post-war Tessars the rear element is not held directly by the retainer ring. You have to unscrew the retainer ring, and the rear element has a mount which fits quite snugly into the hole. I think the best way is to shake it off and catch it with a tissue. |
Alex
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 29, 2005 - 01:16 am: |
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I have had good success too with the vinegar tip, and generally the coating has not been affected, but I did have one lens, a Solinar on an Agfa, where the coating was stripped right off. At least, what used to look like a blue-ish coating has gone, and the lens looks uncoated. Still works fine. |
Milan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 29, 2005 - 02:33 pm: |
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I have used many time ammonia 22° to clean fungus, it works very well and respect coating, but fungus itself destroy coating. So i you clean the glass early in the developing process, you may have excellent results. I the fungus is old, the coating underneath will be destroyed and the "print" of the fungus will remain visible. |
Jonathan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 29, 2005 - 03:33 pm: |
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Is it really necessary to use such strong chemicals? Surely it's more important to clean the rest of the lens barrel and mount, to minimise the presence of fungus inside the reassembled lens. And, to store them well.
See #POST18501
The strong chemicals worry me, but am I being too precious? |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 29, 2005 - 06:36 pm: |
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A most important point Jonathan. Disassembly can scatter fresh spores all over the interior surfaces of the mount.
I think that a constant flow, of a weak active chemical solution is far easier to control than a concentrated solution.Each concentration will have an optimum time,but you will have a greater safety margin with the weaker solution.All very hypothetical; but coatings seem to come in so many forms that you do wonder, when you deal with a particular lens for the first time, if the outcome will be OK.
Glenn. |
Jim Stafford
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 29, 2005 - 09:31 pm: |
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Does anybody know what kind of glue I should use to repair a hard rubber developing tank? |
Gerry Tweedie
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 30, 2005 - 03:54 am: |
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Re: fungus.I have always used a bath of Methylated spirit,with some VERY gentle rubbing with a Q-tip.This has worked every time for me,with no damage to coatings whatsoever. |
Conrad
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 30, 2005 - 07:00 pm: |
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The tried and true remedy is a 50/50 mix of household ammonia and hydrogen peroxide. This has been successful for me where nothing else would touch the stuff. I don't worry much about spores- they're everywhere anyway. If you store the lens in a dry environment, you shouldn't have further trouble with it. If not, you get what you deserve. Some lenses will have deep pits and lines in the glass, and can't be recovered. Other will suffer little damage. You won't know until you have it apart. I've seen more damage on the front surface of rear groups and my theory is the glass types often used there are like candy to fungus. My other theory is that lenses assembled in Japan at certain times of the year are way more susceptable to fungus than German optics and optics assembled in air conditioned plants and kept dry until delivery. You should not be able to remove any coating worth its salt in any common solvent or household chemical. MgF coatings usually have to be polished off. There are exceptions, and if you lose the coating, it won't make much difference compared to having a clean lens. |
Adrian
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, October 09, 2005 - 11:15 am: |
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Thank you for all the suggestions, gentlemen (and any ladies?). Unfortunately the lens is on hold as the shutter on my other Werra has gone mammaries vertical again. However I'm going to try to dig out a mycologist and if I get an interesting opinion I'll post it here!
Adrian |
