As I always take great care of my optical kit, I was perturbed to see something that I thought really shouldn't be where it was, the objective on my two year old foxing scope (Habicht A 4-12x50 ), looked like I had missed the usual cleaning session, there is always a little rain mark or straw dust present after a busy night............. but this stuff was refusing to budge?....... another look through the scope & everything appeared normal!, bugger, it's still there!....... it looked just like a very fine lime or calcium deposit, with the appearance of draining downwards from the top edge of the lens, similar to that found on glass shower doors!. So the phone will be hot monday morning, will post how things are dealt with.