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06-09-2011, 05:44 AM   #1
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Used teleconverter 2x...fungus?

Hi all, here I am with my first post, hoping not to choose the wrong forum...!

I bought a used Kenko 2x APK Teleplus MC4. It is like new as seen from the outside. Also when opened it is in a great condition...BUT...when you look closer, with a good "strong" light and a determined inclination there are some strange spots on the front lens...could this be a fungus? You know, it's really hard to see 'em, but I also took some pictures: the first one without a tripod, and I could see only two spots, but the second shot, made with a tripod, is more "pregnant" here it is:



What do you think about it??

06-09-2011, 08:04 AM   #2
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Could be fungus although it usually has a network of threads running across the glass. Maybe it is just starting or maybe it is something else entirely. Looks more like grease or oil spots than fungus from the photo.

Is it on the inside or outside of the glass?

TC's are not hard to take apart and clean so you might try that route. But if you paid full price I would return it.
06-09-2011, 08:22 AM   #3
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QuoteOriginally posted by jatrax Quote
Could be fungus although it usually has a network of threads running across the glass. Maybe it is just starting or maybe it is something else entirely. Looks more like grease or oil spots than fungus from the photo.

Is it on the inside or outside of the glass?

TC's are not hard to take apart and clean so you might try that route. But if you paid full price I would return it.
Well I paid only 30, but he said it was perfect with nothing on the optics. He also offered the possibility to return back the object, and that's a good thing.

It's on the inside, I tried to clean the lens with a little cloth but it only removed dust.
Well, I think it's easy to open this converter, but fungus could also form again...it's a teleconverter, so it has to be used with other lenses, and the fungus could also pass to the lens I use with it...
If it's a fungus, then I think the only thing to do is to return it and then buy another one from another seller...
06-09-2011, 08:50 AM   #4
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If you look at it with a magnifying glass (loupe?) and you see fibers or tendrils extending out from the central points it is fungus. If not it may be element separation or cement deterioration between two elements.
In either case with a 2x converter you are already introducing image deterioration, and with either of these issues it will be worse.
Personally I would return it and save for something else.
(My avatar is an enhanced image of someone else's fungus problem, to give an idea.)

06-09-2011, 10:17 AM   #5
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I assume this TC has contacts to give you PKA functions. If so, you might try to get a partial refund, remove the glass altogether and use it as a PKA extension tube for macro shot. In many cases, these TC are worth more as extension tubes than what they were originally intended for.

Thanks,
06-10-2011, 08:23 AM - 1 Like   #6
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QuoteOriginally posted by Shadowman85 Quote
but fungus could also form again...it's a teleconverter, so it has to be used with other lenses, and the fungus could also pass to the lens I use with it...
Fungus starts from spores that are in the air all the time. It does not spread from infected lenses unless the fungus present produces a fruiting body and spores. I'm not saying that it cannot happen but I have never seen fungus in a lens produce a fruiting body. Theoretically it could also spread by growing tendrils to another lens but that is not going to happen either.

Fungus needs warmth, moisture and something organic to live on. Without all of those conditions the spores can be present for decades and nothing will happen. It is more prevalent on older lenses because the lubricants and cements used then had a more palatable make up than modern ones. However, I have dozens of 30 year old lenses without any fungus. I also have 2 or 3 that had fungus when I acquired them. I cleaned them properly, disinfected as best I could and I have had no recurrence.

When I see a lens with fungus I can almost guarantee that at some point it was kept in a dark, dank closet or cellar. Or it was exposed to the weather and not dried properly and then kept in a warm, dark location. Easiest way to kill fungus, assuming it is not already dead and all you see are the remaining dried up tendrils, is to put the lens in the sun on a windowsill and let it bake.

Almost always when you see classic fungus in a lens, it is long since dead maybe for decades. All you see are the remaining dead tendrils. If it was still alive it would still be growing, simple biology. And if it was still growing then the entire lens would be covered with white fibers. What happens is the lens got wet, the fungus started to grow, the fungus used up all of the moisture or nutrition available and it died, simple biology. What sometimes happens though is while it was growing it etched the glass enough to ruin the lens or grew in the cement between elements which for all practical purposes ruins the lens.

All that said what you have does not really look like classic fungus but since the lens optics are not in the condition described I would return it. You paid top dollar for this and for that price you should get good condition. As already noted above TC's affect image quality anyway and using one that is not pristine just does not make sense.
06-14-2011, 10:44 PM   #7
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QuoteOriginally posted by jatrax Quote
[much good fungus info]
+1. Great explanation of fungal basics. And I agree on returning the TC. This one is too expensive to just de-glass for tube usage. Plenty of cheap A-type TC's are available. I underpaid on one at US$5, overpaid on another at US$25, but their average of US$15 is just about right.
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