Binocular fogging, outside lens only. Do ...

If it gets foggy on the outside then yes. Just like glass when you breath hot air on it. Most commonly fogging occurs on the outside of the eyepiece lenses. This is because the heat from your body or breath is warmer than the glass and condensation occurs. You can do a few things to help this problem go away. One is to keep a little airspace between your face and the eyecups. If you press the eyecups against your brow with your head bowed a little it lets air flow from underneath. Another is to make a small hole in the eyecups to allow air to circulate. This will void and warranty as it is a deliberate act. Some military binoculars have a small hole for this reason. The other you can do is purchase a fog free cloth. This is a cloth that is imregnated with a chemical that leaves an invisible film on the glass helping keep it fog free. Just ask at a camera store which is suitable for use on coated optics.