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08-05-2013, 09:07 PM   #1
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What is on/in this lens?

I just bought this lens off ebay. It is a FA 100mm f/2.8 macro. When I shined a light through it I saw this pattern on the inside of the elements and am not sure what it is. Can someone help me identify it?

The images I have taken with the lens so far do not seem to have any obvious quality issues. I'm wondering if this is something I should be worried about.

Thank you.

Last edited by vagabond79; 08-05-2013 at 09:19 PM.
08-05-2013, 10:18 PM   #2
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It looks like a residue of some chemicals when a previous owner probably did a horrible job of trying to clean some fungus inside.

At least, it doesn't look like a fungus now.
08-05-2013, 10:24 PM   #3

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It is *likely* cleanable, if done properly.
08-05-2013, 11:26 PM   #4
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I've seen this same pattern before on two of my lenses.

In my case the "stains" were not on the front or rear exposed surfaces but in the interior of the lens. As with your lens, they didn't look like fungus growth.

At that time, after doing some research, I came to the conclusion (never confirmed) that it was a form of degradation in the cement between two united elements. The effect was a notable decrease in contrast. Why this happened?, I never knew.


Carlos U.

08-05-2013, 11:28 PM   #5
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Haze of some form. It may clean of quite well, but paying a pro to do it could be pricey. If you shoot back lit scenes it will show up as flare/ reduced contrast.

I have a cheap 80-200 that I used to use regularly in the rain and it ended up with something similar to this eventually.
08-06-2013, 04:37 AM   #6
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This problem is common to FA 100mm f/2.8 macro lens.

It's a thin layer of clouding (haze, fog, etc.) caused most likely by evaporation of internal grease or oil. The affected element is the one closest to the aperture assembly, towards the front of the lens. It can be cleaned off easily without leaving a trace in most cases. Of course, if you're not experienced with taking a lens apart and cleaning it, you should let a professional lens cleaner do the job. Opening up a lens to clean it can introduce more dust than you started with and also risk the chance of scratching the optics, no matter how careful you are.

I haven't quite figured out why the effect has swirls as if someone has attempted to clean it previously. I have seen it on lenses that I'm certain that it has not been previously opened (no detectable tool marks).

As a side note, not all clouding can be cleaned easily. I have come across clouding (most commonly on M50/1.4) that have resisted all my attempts to clean it. Before anyone says it, yes, I'm aware of cemented elements but this is not the case in this situation.

Also, as one poster mentioned above, the clouding can also occur in between the surfaces of cemented elements as the glue ages. The only remedy in this case is to separate the elements and re-glue, but this is something that even the most seasoned repairers are unwilling or unable to do.
08-06-2013, 04:40 AM   #7
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Thanks to all for your replies. That certainly isn't good news about the lens. I think what I'm going to do is take it to a camera store here, get their opinion on it along with a repair estimate, and then probably try to return to seller. Even though the auction says no returns, the lens was described as having no fungus/haze/etc. so I hope the seller is reasonable and I don't have to open a case with ebay. What a bummer as I was really excited about this lens!

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