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12-23-2013, 04:15 PM   #1
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I have a lens I am unsure of

I have 170-300mm Sigma and spots don't look like it's the glass itself maybe fungus or something with the coating?
When looking at angle I can see what looks like spiderwebs very hairline thin.
Sorry photo not best from cell phone but this best I can show.

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12-23-2013, 04:22 PM   #2
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Might be fungus, cannot be sure from the angle of the picture. If it is only on the inside of the front element it should not be hard to clean off.
12-23-2013, 04:25 PM   #3
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I update shortly with photos with my K-5 using another lens derpy me lol
12-23-2013, 04:32 PM   #4
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As you go deeper the optics seem be very clean with piece of dust/dirt but nothing else seems appear to be a worry to me.


I need some lens experts here so I know what to do. Far as I know it don't look like something I am use to. If more photos needed tell me how I should do it.


Last edited by Pentaxguy22; 12-23-2013 at 04:50 PM.
12-23-2013, 04:49 PM   #5
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Still hard to tell......I see you're in Texas? Where exactly? I'm in FW...if you're in the area (or will be sometime), PM me, if you can ever swing by the office, I can look at it under the microscope and be 100% positive......

Mark
12-23-2013, 04:54 PM   #6
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QuoteOriginally posted by forensicscientist Quote
Still hard to tell......I see you're in Texas? Where exactly? I'm in FW...if you're in the area (or will be sometime), PM me, if you can ever swing by the office, I can look at it under the microscope and be 100% positive......

Mark
That would be great but I actually like 100 miles south....Waco Texas.
12-23-2013, 04:57 PM   #7
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QuoteOriginally posted by forensicscientist Quote
Still hard to tell..
Agree, fungus is often hard to see in pictures, you have to shine the light just right so your eye can see without the glare. I'm leaning to fungus mostly because I don't know what else would cause that if it is on the inside. But spiderwebby looking stuff on the inside of the glass is fungus. How long it has been there and if it is still alive is the real question.

Generally you will get fungus if the lens has gotten moisture inside and then put away in a dark place. Moisture can be rain or just condensation if you went from cold to hot / moist air. It will then grow until it runs out of moisture / nutrition. Which in most cases does not take very long. In almost all cases by the time you see it, it's already dead.

I would make sure to get the lens as dry as possible, either in a drying cabinet or by using silica gel desiccant. UV light can also help kill it. Then check with a shop about getting it cleaned if you don't feel up to that yourself.
12-23-2013, 05:15 PM   #8
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I not sure what happen with this lens as I not the original owner, but best I figure is filter may not been used and or someone did not care for it like they should causing something happen to the coating. If I can kill the fungus then that may be fine, just I had issue trying put a filter on it I never had this much of hassle to put on filter, it goes in like halfway.

12-23-2013, 05:26 PM   #9
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QuoteOriginally posted by Pentaxguy22 Quote
I never had this much of hassle to put on filter, it goes in like halfway.
Make sure the threads are not crossed. And it is most likely that the fungus (if that's what it is) is already dead. Unless it is growing, then it's dead. And if it was growing you would see it covering the whole lens element.
12-23-2013, 05:30 PM   #10
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QuoteOriginally posted by jatrax Quote
Make sure the threads are not crossed. And it is most likely that the fungus (if that's what it is) is already dead. Unless it is growing, then it's dead. And if it was growing you would see it covering the whole lens element.
Yep looking closer seems the lens been hit into something and slightly put the thing out of shape for filter. There are scrape marks on one edge making me assume this.
12-28-2013, 01:09 PM   #11
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QuoteOriginally posted by Pentaxguy22 Quote
I have 170-300mm Sigma and spots don't look like it's the glass itself maybe fungus or something with the coating?
When looking at angle I can see what looks like spiderwebs very hairline thin.
Sorry photo not best from cell phone but this best I can show.
Spider web marks are pretty classic symptoms of fungus.
12-29-2013, 11:55 AM   #12
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Overall photos seem to do good, don't seem to be effecting images in big way, it may not be at it's sharpest potential like it once was.
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