Why do Binoculars Fog Up [and How to Avoid it]

(Last Updated On: June 6, 2019)

Most of the binoculars these days are claimed to be waterproof and fog proof. Even cheaper models come with the waterproof tag. However, does being waterproof essentially means fog proof and weatherproof too?

Unfortunately not. Waterproof and fog proof aren’t the same. Before we start discussing the difference between them, we need to understand why do binoculars fog up?

Why do Binoculars Fog Up?

When you expose your binoculars to extreme temperature/humidity changes, they tend to fog up. Simply speaking, fog is actually formed when minute water droplets get suspended in the air. This actually reduces visibility.

You will notice that when binoculars are exposed to sudden temperature changes, they fog up. The rapid temperature changes actually cause the water vapours inside binoculars to condense. Thus leading to unclear imagery.

Internal and External Fogging 

External fogging means fogging up of an outer lens or outer part of the body of binocular. You can easily swipe away extra moisture with a soft cloth but make sure there is no dirt present already.

Binoculars internal fogging is annoying for the reason that it damages your view because the condensed water gets accumulated inside binoculars.

Apart from the pathetic view, moisture inside can also create fungus which is quite damaging for your binoculars.

Unlike external fogging, internal fogging is not that easy to get rid of but by following this guide below you can easily get rid of moisture inside.

How to Make Binoculars Fog Proof: in 6 Easy Steps 

#1 Dry it Out

One of the easiest and natural way for how to fog proof binoculars and get rid of the extra moisture is their exposure to a warmer climate where there is minimal moisture in the air.

Binoculars are not mostly airtight so natural air will most probably dry out the internal moisture by itself. Be patient and let your binocular “unwind” in the warm wind.

Another way is to use a special fog cloth, that will serve the purpose.

#2 Anti-fog Products

Many anti-fog products are easily available in the market such as creams, sprays, wipes, gels and other chemicals that can be used effectively to fix foggy binoculars.

Don’t just use the anti-fog products you can get your hands on, rather look for the one that is prescribed by your manufacturer.

#3 Use a Desiccant

In case you are short on time or feeling lazy, just use desiccants or silica gel that comes with different items. This way you will never get a problem about why do binoculars fog up.

Place your binos in a ziplock bag along with desiccant like uncooked rice and leave it for 24 hours or more. Rice will absorb all the moisture.

You can use this clever hack for any electrical item such as spotting scopes and monocular etc.

Also Read: what do the numbers on binoculars mean

#4 Fog proof Binoculars

Why not save yourself all this hassle and buy yourself a bino that doesn’t fog up, at all. Nowadays good binos are purged with nitrogen or Argon gas.

Simply speaking it means the inside barrels of binoculars are purged of oxygen gas and in its place, nitrogen or argon gas is used.

Presence of oxygen and moisture is the main reason for fungus growth, so the purging process makes the inside of binoculars fungus proof too, besides making it fog proof and waterproof.

Always remember that being watertight doesn’t always mean fog proof.

Always opt for fog proof binoculars if you are going to use them in conditions where extreme temperature fluctuation is inevitable.

Note that being fog proof does not prevent fogging up of the outer lens. So if that happens you just need to let the binoculars the condensation dry up on its own by letting it adjust to the room temperature.

#5 Spit it Out

Yes as gross as it sounds, spit really works like a charm on binoculars. Just clean the outer lens with spit and you are good to go.

Also Read: The different types of binoculars (and which one is best for you?)

#6 Keep in Dry Place

Always store your binoculars in a dry place and better yet place them in an airtight bag. Place some silica gel packets to avoid condensation and fungus accumulation.

On foggy nights or mornings, to keep binoculars dry put them in a case when you are not using them to minimize fog exposure.


After reading this guide I hope any confusion that you had about why do binoculars fog up are cleared up now. After reading this article you will be better able to clean your fogged up binoculars efficiently in future.

Have a good view, Glassers!

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