Is this dust, mould, water or something else?

[jdawg]

I spotted this inside my lens (L-mount Panasonic 24-105mm 4.0). I bought it used so no warranty/return options. It appears to be on two of the internal pieces. Doesn't seem to impact performance. Should I be worried?

 

[RAZKY]

I spotted this inside my lens (L-mount Panasonic 24-105mm 4.0). I bought it used so no warranty/return options. It appears to be on two of the internal pieces. Doesn't seem to impact performance. Should I be worried?View attachment 261417

View attachment 261415View attachment 261416

I cannot say exactly what they are, but they sure don't look good! I'd keep using the lens and hope those spots don't grow to where they affect image quality. If they do, it may be a parts lens. Hoping that's the last used lens you buy sight unseen from a stranger without a return policy!

 

[smoke665]

It's hard to tell exactly from the pictures, but it looks more like fungus than dust. An easy test is to shine a light through the lens and inspect with a magnifier. Fungus will look like hairy dots of fuzz.

The sure fire method of treating is to have it disassembled and cleaned. However I've heard that exposing the open lens to strong UV light, like the sun for a few days will kill it. Left unchecked it will eventually etch the surface.

 

[cgw]

Fungus infections usually have spidery uneven look. This resembles oil droplets on a lens exposed to prolonged high temps I bought and had cleaned, or so said the poor Nikon tech who tidied it up. Way too prominent for dust alone. Just a guess...