White swirl

I've noticed a recently bought lens has a white circle on the inside of the front element. It looks a bit perfectly circular to be fungus, could it be that the inner element has scratched against the inner lens barrel?

Doesn't seem to affect performance - very happy with this lens for the price I paid for it! Just don't want to have an outbreak of anything nasty on my other lenses.

It could be separation between some of the elements, where the cement has failed. Sometimes it appears as a circle of white dots.

Is it an old lens?

It's a Sigma 70-300 APO. Your explanation sounds very plausible John. Now I look closer there's an outer ring (faint but complete) and an inner ring (partial but more distinct, and glinting like scratched glass).

Well it still takes a 'nice shot'. Got the chance to have a play with it when my niece was brought round this afternoon.

What a great expression! Looks like the lens will be useful enough.

Cheers John. I'm no 'wildlife photographer', so this one will do me OK!