70-200 F4 IS Ring Discoloration

Hoping someone here may throw some light on this issue. I have 70-200 F4 IS with date code of UU. I am seeing some discoloration of the black rings used for zooming and manual focus. I have seen older versions of this lens where the rings are not discolored. Though this has no effect on the quality of the images it produces, I just want to make sure that my lens is not one off in this issue. I have attached some pictures for reference.

Thanks in advance for any information.
Vinay

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Does it clean off? It looks like very typical dirt/dust/sweat buildup to me, since it's only in the recessed regions.

Tim Kostka wrote in post #9641940
Does it clean off? It looks like very typical dirt/dust/sweat buildup to me.

Appreciate the response, but I am afraid of cleaning it with any liquids. Any suggestions?

Tim Kostka wrote in post #9641940
It looks like very typical dirt/dust/sweat buildup to me...

Agreed.

Try hitting with a set of low-intensity rubbing alcohal dipped Q-tips...
Or some hand sanitizer wipes; do that on my 70-200mm f/4-L all the time since I persperate alot in the hands.

- Erik

Its normal. A lot of older lenses do it over time. IIRC its something to do with the agent they use to cause the rubber to release from the mold during manufacturing. Dont worry about it.

Looks to me like dried sun screen. I get that on some of my guns from time to time during the summer competitions. I bet it cleans right off.

kash80 wrote in post #9641965
Appreciate the response, but I am afraid of cleaning it with any liquids. Any suggestions?

Well, first I'd just try a damp (with water) paper towel or rag. That's always safe, as long as it's not too wet. Rubbing alcohol usually works well for cleaning, but I've never tried it on a lens. Personally, I'd just ignore it.

No need to obsess over it...nothing to worry about. All (almost) elastomers do this over time. Oils from skin, sunlight, chemicals such as sunscreen all have an effect on the rubber.