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yusuf · 08-20-2013, 10:36 PM

I am planning to buy a lens locally and noticed this on the rear element. Any idea what is this? First I thought that it was fungus but after some closer inspection, it looks something else. Another clue is, I noticed some green fluid leakage at mount.

Any idea?

Thanks
Yusuf

Attached Images

manntax · 08-20-2013, 11:06 PM

looks perhaps like elements separation - and also something could have started to grow in between them. I would probably avoid this lens.

**kiwi_jono** · 08-20-2013, 11:09 PM

Originally posted by manntax

looks perhaps like elements separation - and also something could have started to grow in between them. I would probably avoid this lens.

+1. I have seen a lens do this before and it looked very much like this.

BTW: great job photographing he problem - I have tried shooting problems on elements before and it can be surprisingly difficult to get such a clear view of it.

yusuf · 08-20-2013, 11:42 PM

Any idea what could have caused this?

elliott · 08-21-2013, 12:44 AM

Originally posted by yusuf

Any idea what could have caused this?

Mostly just age, though heat can cause the cement to break down faster.

It is repairable, but it is costly to have it done. I've always wanted to try it myself, but never had a lens with the problem that would be worth repairing. I have saved a few good cemented elements out of otherwise junk lenses to practice on if I ever get a good lens that I would actually want to save. The cement isn't cheap, so I want a really good reason to attempt it.

yusuf · 08-21-2013, 04:36 AM

Originally posted by elliott

Mostly just age, though heat can cause the cement to break down faster

Thanks, yes looks like bad storage condition caused it. It's usable right now but according to a local repair shop, it will inevitably spread. Is that the case with all such element separation problems?

manntax · 08-21-2013, 06:10 AM

Originally posted by yusuf

Thanks, yes looks like bad storage condition caused it. It's usable right now but according to a local repair shop, it will inevitably spread. Is that the case with all such element separation problems?

the short answer is : Yes. The long one - it depends , takes time and etc. but sooner or later it will worsen and furthermore - it becomes vulnerable for fungus and hazing in between the elements separated. So the best advice is : Avoid - or in case of valuable lenses - Repair. And THAT is probably another topic

-manntax

08-20-2013, 10:36 PM	#1
yusuf Pentaxian Join Date: Nov 2008 Location: Bangalore Photos: Gallery Posts: 2,471	Fungus or something else? I am planning to buy a lens locally and noticed this on the rear element. Any idea what is this? First I thought that it was fungus but after some closer inspection, it looks something else. Another clue is, I noticed some green fluid leakage at mount. Any idea? Thanks Yusuf Attached Images

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08-20-2013, 11:06 PM	#2
manntax Veteran Member Join Date: Jan 2012 Photos: Albums Posts: 1,972	looks perhaps like elements separation - and also something could have started to grow in between them. I would probably avoid this lens.

08-20-2013, 11:09 PM	#3
kiwi_jono Loyal Site Supporter Join Date: Dec 2009 Location: Christchurch, New Zealand Photos: Gallery \| Albums Posts: 2,407	Originally posted by manntax looks perhaps like elements separation - and also something could have started to grow in between them. I would probably avoid this lens. +1. I have seen a lens do this before and it looked very much like this. BTW: great job photographing he problem - I have tried shooting problems on elements before and it can be surprisingly difficult to get such a clear view of it.

08-20-2013, 11:42 PM	#4
yusuf Pentaxian Join Date: Nov 2008 Location: Bangalore Photos: Gallery Posts: 2,471 Original Poster	Any idea what could have caused this?

08-21-2013, 12:44 AM	#5
elliott Inactive Account Join Date: Dec 2008 Location: North Carolina Photos: Albums Posts: 1,720	Originally posted by yusuf Any idea what could have caused this? Mostly just age, though heat can cause the cement to break down faster. It is repairable, but it is costly to have it done. I've always wanted to try it myself, but never had a lens with the problem that would be worth repairing. I have saved a few good cemented elements out of otherwise junk lenses to practice on if I ever get a good lens that I would actually want to save. The cement isn't cheap, so I want a really good reason to attempt it.

08-21-2013, 04:36 AM	#6
yusuf Pentaxian Join Date: Nov 2008 Location: Bangalore Photos: Gallery Posts: 2,471 Original Poster	Originally posted by elliott Mostly just age, though heat can cause the cement to break down faster Thanks, yes looks like bad storage condition caused it. It's usable right now but according to a local repair shop, it will inevitably spread. Is that the case with all such element separation problems?

08-21-2013, 06:10 AM	#7
manntax Veteran Member Join Date: Jan 2012 Photos: Albums Posts: 1,972	Originally posted by yusuf Thanks, yes looks like bad storage condition caused it. It's usable right now but according to a local repair shop, it will inevitably spread. Is that the case with all such element separation problems? the short answer is : Yes. The long one - it depends , takes time and etc. but sooner or later it will worsen and furthermore - it becomes vulnerable for fungus and hazing in between the elements separated. So the best advice is : Avoid - or in case of valuable lenses - Repair. And THAT is probably another topic -manntax

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