Good link - looks like the most plausible explanation is:-
Condensation on the lens?
Quote:
|
Condensation inside some sort of housing would be my guess. If the drop were directly on the lens it would be effectively invisible. Put it a few inches/feet away and have the camera shooting with a very deep depth of field (as you would with a small aperture) and it would look just like that anomaly.
|
But then why dosent it show on all other pictures?