Help! Canon EF 70-200mm f/2.8L IS II USM

[jdiplo9]

Hi,

Recently I bought a Canon EF 70-200mm f/2.8L IS II USM in fantastic condition on eBay. However when I was inspecting the inner glass I noticed something that is either glue or fungus in within. It's along the rim of the inner chambers. Please could someone explain what this could be?

Thanks

J

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IMG-20210202-141901-01

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