I understand the benefits of nitrogen filled but will non-nitrogen binocs always fog up in cold weather?
I'm almost embarrased to ask but if I remove the eye pieces from a binoc, put everything into a baggy, suck the air out, and then at my local tire dealer pumped the bag full of nitrogen and reaassemble the eye peices with the baggy sealed, would I have in affect at least replaced the majority of the air inside with a decent percentage of nitrogen? Thanks.
I live in Winnipeg, Manitoba where it gets down to -30 C. in the winter, and I take my vintage binoculars (about 50 different ones made 1900 - 1980 by Zeiss, Ross, Barr & Stroud, Nippon Kogaku etc.) out frequently in this weather and have never had a problem. Mind you, I baby them - when back inside they sit until all exterior condensation has evaporated and then many go into a ziplock plastic bag with a desiccant pouch. It would be another story if I used one in the field all day where it got damp, camped out for the night, then continued to use it the next day. Under those conditions I think some would fog up. Biggest problem in really cold weather is the diopter and central focusing mechanisms becoming stiff and even sometimes immovable (depends on the type of lubricant) and the exterior of the eyelens getting fogged or frosted when viewing.
It really makes no difference if there is nitrogen air or argon, optically. It is just to keep water vapor out and seal it. So nitrogen is a convenient cheap gas.