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04-21-2013, 06:25 PM   #1
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Gold fungus or something else?

I bought a lot of lenses (all with problems) and one was a pentax A 50mm 2.0. It was described as having fungus/debris from a very large reputable dealer. It had a splotch of gold something in the middle. I guess they could have meant fungus or debris? There was none of the typical snowflake or spider web or filament type fungus. What shocked me is that it cleaned up perfect. There is absolutely no sign of damage whatsoever. I have cleaned lenses with fungus before and know what the damage looks like (even when it just discolors the coating which seems to adversely effect contrast and sharpness). This lens had none.

So whats the gold stuff? It becomes when soluble when cleaned with lens tissue and lens cleaning solution, or at least it will smear across the lens. It is not just reflection from the fluid (it remains when dry and must be cleaned off). One of the other lenses had this gold stuff (looked like someone dissembled it already and may have tried to clean it, and it had obvious fungus damage though I saw no fungus). I have seen it a few times so its not an isolated thing (though seems to accompany suspected or definite fungus).

I think the first time I have seen that gold stuff was a box of 10 vintage vivitar filters. They had an obvious coat of fine, faint, white filament fungus across the whole surface of them all, and it was on the back side of them all. When cleaned, most of the coating came right off but the glass was undamaged. I assumed the fungus ate the coating. These were filters so no lubricant was on them (so its not lubricant).

I'm just really dying to know what this gold stuff is (just curiosity). Maybe a byproduct of many different kinds of fungus, including some that do not harm coatings and glass? Does anyone have a clue?

04-21-2013, 06:53 PM   #2
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Probably just a spot from some liquid - coffee, tea, cola drink, soap bubbles - who knows???
04-21-2013, 07:39 PM   #3
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Was it the actual coating, which had been chenically changed by the fungus, then you wiped it off?
04-22-2013, 03:23 AM   #4
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QuoteOriginally posted by monochrome Quote
Was it the actual coating, which had been chenically changed by the fungus, then you wiped it off?
Thats what I thought when I first saw it on the vivitar filters. On them, most of the coating had been eaten away. On this latest lens though (the pentax A 50mm 2.0), after cleaning it off, the coating seemed to be fully intact. It still had that colored dim reflection that you get with a coated lens on the surface that it was cleaned off of. The coating seemed to be unblemished at all.


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