Small dots or bubbles on inner lens element?

Got a 300mm F4IS refurb from Canon. I checked the inner elements with a flashlight. And what I found was a large array of what looked like tiny bubbles on one of the inner elements. They were segregated along the periphery of the element. Not sure if these are bubbles or something else?


Sorry not the best pictures of it but I snapped off a few real quick.

Unless they affect the image I would not worry about it. I would think it has no effect IMO

Is that the beginnings of fungus / mould?

well it covers about 30% of the lens element. I read somewhere that this was from the cement holding the element together possibly? Hmmm... not sure what to think. I don't think it's mold because of the fact that this is a refurb direct from Canon. So that would make that seem unlikely. It definitely looks like a huge array of tiny bubbles.

Disappointed a bit since this was a replacement already for the previous lens they sent that had scratches on the front element.

I noticed the same thing in one of my lenses. I don't think it's mould. I don't really believe it could be mould because I live in a very dry place. The humidity in my house is rarely above 20%. Also, it has been completely unchanging for many years. It does not affect image quality at all.

So is this an issue and should I request another one? None of my other lenses exhibits anything like this.

Its definintly looks microbial. Even if it isnt, whatever it is should not be in there on a newly factory refurrbed lens. I would send it back right away.

Dillan_K wrote in post #15726547
I noticed the same thing in one of my lenses. I don't think it's mould. I don't really believe it could be mould because I live in a very dry place. The humidity in my house is rarely above 20%. Also, it has been completely unchanging for many years. It does not affect image quality at all.

Lenses don't catch fungus inside your house. They catch it outdoors.

And if it is fungus, its only going to get worse. send it back.