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03-14-2017, 12:25 PM   #1
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Something in a lens glass

Hi, I just got Tamron 80-200.
Can anyone explain what is that? Lens looks like new, front glass is perfect but from back there are some strange tiny bubbles in a glass. I do not see any problems with a quality for now, but I am wondering can it come some in the future?

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03-14-2017, 12:34 PM   #2
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Fungus?
03-14-2017, 12:49 PM   #3
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QuoteOriginally posted by BullsOnParade81 Quote
Fungus?
Lens was stored in a original box with silica gel so I am not sure, but may be.
03-14-2017, 01:01 PM   #4
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QuoteOriginally posted by dcshooter Quote
If it looks like bubbles, it's more likely migrated oil.
Is it bad?

03-14-2017, 01:26 PM   #5
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QuoteOriginally posted by dcshooter Quote
Not as bad as fungus would be. Tamron coatings are very prone to permanent etching from fungus, whereas oil can usually be cleaned right off.
Would You recommend to take it to service centre immediately, or it is not a big issue for lens quality.
03-14-2017, 01:45 PM   #6
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Yes, its oil that has deposited itself on the glass. This most often happens when lenses are left in a hot environment (attic, car trunk, etc.)

Trouble is, it's quite hard to get at the surfaces that are most affected. That Tamron will have to be stripped right down to its basic components. It's at least a couple hours work on a repair bench, and it can get hard to justify, economically.
03-15-2017, 01:06 AM   #7
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This lens has a reputation for being a decent performer compared to its peers. It would be well worth the effort to repair.

QuoteOriginally posted by Ontarian50 Quote
That Tamron will have to be stripped right down to its basic components.
The image shows the problem from the mount end - the oil appears to be on the rear of the front cell of the optical assembly, so it should be relatively simple to get to.
03-15-2017, 08:02 AM   #8
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QuoteOriginally posted by Digitalis Quote
This lens has a reputation for being a decent performer compared to its peers. It would be well worth the effort to repair.



The image shows the problem from the mount end - the oil appears to be on the rear of the front cell of the optical assembly, so it should be relatively simple to get to.
If the OP's lens is the 2.8, then it justifies a few dollars more on the repair bench, for sure.

But the OP said the front glass was clean, and I'd bet it is. His photo is from the rear because that's where he can best see the oil residue - and I'll bet its on the element surface in front of the aperture assembly. For some reason that's where it always ends up, Tamron or otherwise.

03-15-2017, 08:07 AM   #9
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QuoteOriginally posted by Ontarian50 Quote
Yes, its oil that has deposited itself on the glass. This most often happens when lenses are left in a hot environment (attic, car trunk, etc.)

Trouble is, it's quite hard to get at the surfaces that are most affected. That Tamron will have to be stripped right down to its basic components. It's at least a couple hours work on a repair bench, and it can get hard to justify, economically.
Is it really oil? Blades seems to be pretty clean.
03-15-2017, 08:56 AM   #10
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QuoteOriginally posted by greenas Quote
Is it really oil? Blades seems to be pretty clean.
Yes, it's a type of oil. However, camera lenses don't come "oiled" from the factory.

The grease used to lubricate the helicals and zoom cams can degrade and leach out a fine oil over time, especially if subjected to a hot environment. Vapour from that oil deposits itself on a convenient surface - which is usually the innermost and most inaccessible lens element. Its essentially a sweaty film that beads up on glass.

That's what makes the old Super Takumars so amazing. The darn things are pushing 50 years old, and the grease is still intact, and the helicals are still smooth. What wonderous grease Pentax used is a mystery.
03-15-2017, 10:25 AM   #11
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It is a Tamron Adaptall-2 SP 80-200mm f2.8 LD, so I think it is worth to be cleaned.
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