Binoculars fogging in the cold, any solutions?

[Fahndar]

This winter turned out to be very cold: we have -20C to -27C at night. My biggest problem while observing is the fogging up of the eyepieces on my binoculars from the body heat. I cannot observe for more than 1 minute, after which I had to switch to another set of binoculars and wait for the fog to dissipate and so on rotating binoculars and waiting. This is really frustrating. Anyone has a solution to this? Any help will be greatly appreciated!

[rory]

I don't know how much a home made few shield would help keep fogging at bay. -20 brrrr.

[acey]

It's possibly your breath that's causing the fogging - try headgear that will lessen the effect. Take care not to inadvertently breathe on the lenses when lowering the bins from your eyes. Keep the eyepieces capped when you aren't looking through them. Or put some kind of heat source (e.g. a chemical "handwarmer") inside the eyepiece end of your binocular case, and put the bins in there for a couple of minutes if they steam up - it ought to clear them.

I've had similar problems with the eyepiece of my telescope finder steaming up, and my guess is that breath has a lot to do with it, though my solution is to keep it capped when I'm not looking through.

[Fahndar]

Thank you for the input. I will try some type of warming solution for the eyepieces. I was thinking about using a hair drier to warm my glasses and binoculars. I don't think it's the breath because my glasses are fogging up even quicker than binoculars when I have then on and I do not breath on them.

[jkwhinfrey]

I've found that my binoculars eye pieces fog because my eyes are watering sometimes because of tiredness, but also the cold. I noticed when only one of them was watering, and sure enough, only that EP fogged. Drying the eyes and warming the EPs is the best/only solution I've found.

[Mr Q]

   Not only is your breath and eyeball moisture a source of water vapor that fogs on cold surfaces, your body heat rising around you can also be a source. Other than keeping one pair inside a large pocket near your body while using the other binocular, there is not much you can do..