Birdwatching Dot Com


Birding FAQ

Birding Tips







The Binocular Advisor

Optics Myth 7:

I don't need waterproof binoculars. I don't go out in the rain.

Waterproof wet binocular

REALITY - You do need waterproof binoculars. Even if you never go out in the rain.

When warm, moist air contacts a cool surface, water condenses. That's why your car's windshield fogs up when you breathe inside your car on a wintry day and your bathroom mirror fogs up when you take a shower.

It's also why your binoculars may fog up inside when they go from a cool environment, such as an air conditioned car or house, into a warm or moist environment, such as outdoors in summer, or near the ocean, not to mention a trip to the tropics. Even if they eventually dry out and clear up again, the trip or the day's birding may be ruined.

A waterproof binocular is prepared for changing climate. Its insides are isolated from salt spray and dust, and if it gets dusty on the outside, you can rinse if off under the tap. Waterproof binoculars are sealed and filled with a dry, inert gas that contains no water vapor to condense inside.

Since waterproof binoculars are no longer expensive, it makes sense to ensure that you're getting this feature in any binocular costing over $100. Look for the expression "nitrogen purged" or "nitrogen filled."

Copyright 2006 Michael and Diane Porter


Sharp-shinned Hawk

Optics Myths and Misconceptions