My Fujinon binoculars are at least fifteen years old
now and still working like new though they look a little
beat up.

Amazingly they do not fog up inside the lenses.

They are filled with "dry nitrogen" at the factory
but I find it hard to believe this inert gas has
stayed in there over all the long years.

Anybody here happen to know how long nitrogen
really remains in those filled binoculars?

CN