Ski shops sell anti-fog cloths and anti-fog sprays for ski goggles. 
Should work for binoculars, too.  You wet a corner of the cloth 
slightly, then rub it on the outer surface of the lens.  This works 
even when the lens is cold.

Now if I could keep my glasses from fogging up when I press them 
between my face and the binoculars on summer days when the 
temperature is warm and the humidity is 95%!


June Tveekrem
Columbia, Howard Co, MD
tweekiebird AT toadmail DOT com


Bob Hartman wrote:
> Paul, it will help if you try to keep them warmer than the ambient 
> environment, maybe by keeping them inside your jacket when they aren't 
> actually being used.
> 
>     Bob Hartman
> 
> 
> Chris & Paul Woodford wrote:
> 
>> the exterior surfaces of the [binocular] lenses got 
>> water on the them and fogged, which impaired the view.  Does anyone 
>> have suggestions on how to avoid or recover from that situation in the 
>> field?
>>
>> Paul