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Ezio
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 24, 2004 - 05:08 am: | 
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I started a tread down here about a Miranda 135mm lens which suffers from what I originally identified as fungus covering the internal walls of the barrels, and I received good advice pointing at this being rather aluminum corrosion/oxidation. Well, things are more complicated, and I thus reopen a tread because the info might be of some use to somebody other.
I have been able to unscrew the front lens element and remove the second element, which looks like two or three pieces of glass cemented together to form a cylinder some 7-8cm long. The fungus or whatever is not on the metal barrel as I thought; rather, it grows on the flat black painting on the interior of the cylinder's mid element, and thus it must be fungus. However, it seem incapable to affect the free glass. Alternatively it is possible that the painting is simply deteriorating, but in this case there should be chips and flakes everywhere inside the lens.
I don't intend to go through taking the cylinder apart and then recementing its elements, but just for the sake of it, what is likely to happen if I place the f--ed thing in a microwave oven? Not that I'm worried to ruin the lens - but if I cause the microwave to explode I'll be in deep you know what... |
Winfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 24, 2004 - 08:30 am: |
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I don't know how an organic cement (as it was used until the 70s or so) will react when put in a microwave oven. But I can't see any reason for this.
However, you can scrape off the black paint on the lens edge and replace it by black matte model craft paint. |
Ezio
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 25, 2004 - 08:51 am: |
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Winfried, "I can't see any reason for this": do you mean that there is no reason to put the lens in microwave (that is, it would not kill fungus), or that there is no reason to fear an explosion? I seem to remember having read that microwaving sealed air spaces might lead to unpleasant consequences. The black paint is on the inside of the lens and is not accesible unless I de-cement it. |
Lars
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 26, 2004 - 08:30 am: |
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Please, don´t put cemented lenses in a microwave oven! First of all, trapped moisture or air bubbles WILL cause an explosion. Further more, microwaves will NOT kill fungus, as these organisms are smaller than the wavelength of the microwaves and will not be affected at all.
The best way to remove fungus is to use contact lens cleaning fluid. This is specially formulated to take care of such problems. I have used it now for over two years, and the fungus has not reappeared in the lenses I have cleaned. |
Jackson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 26, 2004 - 11:29 pm: |
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> microwaves will NOT kill fungus, as these organisms are smaller than the wavelength of the microwaves and will not be affected at all.
Microwave ovens work on the principle of heating water molecules. The size of the object that contains those molecules is relatively unimportant to the process. If fungus contains water, the water and fungus will be heated.
I agree that placing a lens in the microwave seems an unnecessary risk to both the lens and the oven, not to mention the photographer. |
Rob
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, December 03, 2004 - 10:59 am: |
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You could try a cat... |
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