Mickey,It has only been in the last 20 years or so that Zeiss has used Nitrogen in their scopes. They used to claim that their scopes were sealed so well that they would not leak or fog. Obviously an optimistic statement.

For years, I have used best Leitz (Trinovids) and Zeiss earlier binoculars that were only sealed, water resistant; not truly waterproof, but under normal field conditions, they "would not leak or fog" we were told. Well, I have found them to not leak or fog, even in Oregon rain, so have come to the conclusion that true waterproofing so common today is not needed; is only a selling gimmick, unless you were going to use them underwater, such as in skin diving.