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02-26-2011, 01:52 PM - 4 Likes   #1
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Huge test on the influence of fungus in lenses (on 9 lenses)

I put online the results of this huge test lead on 9 lenses 8 affected and 1 clean for reference, without problems. About 10 hours of work (setting up the used test protocol, shooting, results compilation, sending it on my site), but now we have a solid information about the real influence of fungus in lenses :
Champignons, le grand test - Partie 1 - Takumar - The eyes of the Spotmatic
Some of you could be surprised by the results

Mods : if there's a better place for this thread, do not hesitate to move it, I was not sure where to place it

02-26-2011, 02:04 PM   #2
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Using Google Chrome, I got the translation of "mushrooms".

Great info.
02-26-2011, 02:15 PM   #3
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Wow, I've been waiting for this test for some time. + Rep. The study is very interesting. I am surprised it made even the difference it made. But except for the worst performer at its worst aperture, the differences are so slight that a minor touch of the contrast slider and you are fine. I do have one question about your procedure: did you use a lens hood for all of these or not (as that could affect the results), and if so what hood? Also, are you going to put up an english version (although Google translate is serviceable)? Thanks to you the price for fungus infested lenses is going to go up

I'd hope the mods move this to the lens section, by the way.
02-26-2011, 02:23 PM   #4
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QuoteOriginally posted by metalmania Quote
Using Google Chrome, I got the translation of "mushrooms".

Great info.
That's normal, "champignon" in french means both mushrooms (the ones that can be eated) and fungus (the ones that comes with humidity, in lenses)

QuoteOriginally posted by macTak Quote
Wow, I've been waiting for this test for some time. + Rep. The study is very interesting. I am surprised it made even the difference it made. But except for the worst performer at its worst aperture, the differences are so slight that a minor touch of the contrast slider and you are fine. I do have one question about your procedure: did you use a lens hood for all of these or not (as that could affect the results), and if so what hood? Also, are you going to put up an english version (although Google translate is serviceable)? Thanks to you the price for fungus infested lenses is going to go up

I'd hope the mods move this to the lens section, by the way.
No lens hood, because the idea was also to see if there are problems regarding to flare resistance (you can see that the lamp could lead to some flare if there should be one)
As for the whole site, an english version is planned (altough I think google should translate it to something "understandable" in english, and many english native speaking people seems to have learnt some french during studies), but I would like to finish some parts of it in french first. This test could be one of the first translated parts, but I do not think I will have enough time to do it quickly...

02-26-2011, 02:41 PM   #5
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Wow, thank you very much for all the work you have done and have shared with us. The results are very interesting.

I have a couple of lenses with a single strand of something in each. It looks like a piece of lint from clothing, but I'm baffled as to how it could get inside. I wonder if that could possibly be fungus (or mushrooms!). Or just lint. I have been wanting to get it out, but after seeing this test, I'm not nearly as worried as I was before. Perhaps I'll put off disassembling them until I know more about what I'm doing.

Thank you again. Nice work!
02-26-2011, 03:44 PM   #6
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that's good to know ! Thanks a lot for this usefull test.

Merci CarbonR le Clermontois ^^
02-26-2011, 10:46 PM   #7
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QuoteOriginally posted by CarbonR Quote
No lens hood, because the idea was also to see if there are problems regarding to flare resistance (you can see that the lamp could lead to some flare if there should be one)
Yes, but now you have me curious if and how much using a lens hood would improve upon the results (after all, I do always use the Takumar 135/150/200mm hood with this lens). Such a test might be helpful for further determining real world performance, where generally hoods are used, especially in such conditions where flare is possible and extra shading protection is advisable.
02-27-2011, 01:26 AM   #8
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I can't redo the test, as some lenses already have been cleaned and sold, but I still have the most affected ones. I might try to test with and without hood. I would say it can improve a little bit the contrast, but I'm sure it won't improve sharpness

02-27-2011, 02:19 AM   #9
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Well... this reminds me of a page I stumbled upon a long time ago.

WARNING: THE PAGE BELOW CONTAINS PICTURES OF *BADLY DAMAGED* LENSES THAT SOME VIEWERS MAY FIND FRIGHTENING AND/OR SHOCKING!

Lens damage influence on picture quality
02-27-2011, 12:34 PM   #10
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QuoteOriginally posted by CarbonR Quote
I can't redo the test, as some lenses already have been cleaned and sold, but I still have the most affected ones. I might try to test with and without hood. I would say it can improve a little bit the contrast, but I'm sure it won't improve sharpness
Well, just buy more fungus-infested lenses, after all you only had 8 to begin with

I agree that a full redo is not at all warranted (I hope there are better things to do with one's time), but it would be interesting to do a short test with one or two of the ones you have left.
02-27-2011, 01:24 PM   #11
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Thank you very much for the huge amount of info!
02-27-2011, 05:45 PM   #12
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QuoteOriginally posted by Howdy Quote
Well... this reminds me of a page I stumbled upon a long time ago.

WARNING: THE PAGE BELOW CONTAINS PICTURES OF *BADLY DAMAGED* LENSES THAT SOME VIEWERS MAY FIND FRIGHTENING AND/OR SHOCKING!

Lens damage influence on picture quality
That's consistent with this great posting about lens damage.

LensRentals.com - Front Element Scratches
03-06-2011, 10:48 AM   #13
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I posted before and after pix of fungus clean up with a Vivitar 400mm/5.6 a while back. The thread-like fungus affected about 30-percent of the inside surface of the objective lens.

There was no apparent change in overall sharpness. The noticeable difference was in better contrast and color saturation in the out-of-focus background areas after cleaning.

H2
03-07-2011, 09:01 AM   #14
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somewhat related: what kind of effect does oil on the aperture blades have? does it just keep them from moving freely? how does oil get inside the lens???
03-07-2011, 11:14 AM   #15
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QuoteOriginally posted by wehavenowaves! Quote
somewhat related: what kind of effect does oil on the aperture blades have? does it just keep them from moving freely? how does oil get inside the lens???
Oil on aperture blades usually results from grease in the focusing sleeves migrating to the aperture assembly when softened to liquid state in high temperature conditions. When it's cooled the oil/grease becomes viscous or even glue-like and causes the individual blades to move slowly or not at all.

Some lens brands are known to be more prone to this condition than others. Use of newer lubricant formulas has greatly reduced the problem in newer lenses.

Those older manual focus lenses which allow easy access to the aperture mechanism can often be restored to normal operation with a few drops of naphtha or lighter fluid on the blades.

H2
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