Even if you only plan to go bird watching in fair weather, waterproof binoculars are highly recommended. It’s best to look for birding binoculars that are waterproof.
There are a number of reasons why.
Sudden temperature changes can cause condensation to form on the internal surface of lenses.
For example, as you leave your cosy interior to go out into a chillier atmosphere, or as you move from an air-conditioned room into a warmer environment, your binoculars are at risk from some moisture getting inside them.
Why do my binoculars fog up?
Moisture forms when warm air meets a cool surface. As the moist air lands on the cooler surface, such as the glass of your binoculars, condensation will fog up your lenses.
Unfortunately with binoculars that are not totally airtight, this fogging can also form on the inside. This internal fogging can be difficult to get rid of.
Clearly this has a negative impact on the image clarity because you are looking through a lens covered with tiny water droplets.
Can I defog or fix cloudy binoculars?
At some point, the internal moisture may dry out and the lenses clear. But there is no way of knowing how long this will take.
There is also a risk that the water may leave marks on the lens or on the prism. This would hinder any clear view.
Left unchecked, moisture inside may cause bacteria to begin growing. The presence of mildew, mold or fungus can damage the internal optics. Mold also reduces contrast.
If this mist forms internally there is not a lot you can do.
It is best to leave your binoculars to dry out. Make sure they are dry rather than putting them away or storing them.
The difficulty of clearing the moisture that forms inside non-airtight, unsealed binoculars is the best reason to invest in a pair designed to be waterproof.
How do I keep my binoculars from fogging up?
Having a properly fogproof pair that prevents air or water entering will stop the problem of internal fogging.
Nowadays, it is possible to find very affordable binoculars that are both fogproof and waterproof.
Some cheaper binoculars are not at all waterproof and are therefore at risk of fogging up.
If you look for binoculars that are specified as fogproof, you will find that they are also waterproof. This is due to the way that fogproof binoculars are made.
Do you need waterproof binoculars?
Waterproof binoculars will prevent moisture, dust and debris from entering the binoculars. This helps to protect the internal mechanisms. But they are not designed to prevent fogging.
So binoculars that are waterproof, though, may not necessarily be fogproof.
What does fog proof mean?
The best fogproof binoculars for birding have been made fog proof through a process in which they are totally sealed and filled with a gas that does not condense when subjected to temperature changes.
All of the openings on the binoculars are hermetically sealed with O-rings. The O-rings form an airtight and watertight seal.
The purpose of this is to guard them against any moisture entering. This stops mold or fungi growing, and corroding the instrument.
The best anti-fog treatment for binoculars:
How do you fog proof binoculars?
Some binoculars have the normal air taken out and replaced with gas. Binoculars treated in this way are described as ‘nitrogen-filled’ or ‘nitrogen-purged’.
This is done during the final stage of its manufacture by pumping in dry nitrogen gas to purge the inside of the binocular of any air.
The gas is pumped through a valve hidden within the casing of the binoculars. The valve allows the gas to be changed or topped up.
Why are binoculars filled with nitrogen?
The objective of putting a dry, inert gas inside, instead of the normal atmospheric mix of oxygen and nitrogen, is to protect the binocular from internal fogging when exposed to fluctuations in temperature.
The theory of this is based on the slight positive pressure of the nitrogen. This positive pressure prevents the air, which is lower pressure, from entering the body of the binocular.
In addition, because nitrogen cannot hold moisture, it means no fog can form on the inside lenses.
Are nitrogen-filled binoculars any good?
Binoculars filled with gas are more reliably waterproof and fogproof because they are airtight.
Nitrogen is the most commonly used gas in this process. Other noble gases such as argon, and less often, krypton, can also be used.
What’s the difference between Argon and nitrogen?
The difference between Argon and nitrogen, in this context, is that the atoms of Argon are larger. Argon has a higher atomic weight.
No matter how carefully sealed the body of the binoculars, they cannot be totally gas-tight and will be prone to leakage over time.
Which is better, Argon or nitrogen?
Argon’s bigger molecules make it more resistant to diffusion, meaning that it will take longer to disappear from the inside of the binoculars.
Some binocular manufacturers use Argon to fill the interior. They use Argon because they believe it will be more resistant to diffusion. Therefore it should last longer than nitrogen.
Those manufacturers who use nitrogen believe that it is as effective as Argon because they are both dry gases.
Can binoculars get wet?
Manufacturers describe the qualities of their products in various ways to make them attractive. Here are some of the descriptions you might encounter:
| Special treatment | Usage and risks | |
| No Rating | No weatherproofing | Should not be used in the rain or near water. Moisture/condensation can form inside, causing damage |
| Weather Resistant | Often has a seal to prevent moisture entering the interior. Usually contains low-moisture ambient air | Can be used in most normal conditions without fogging |
| Waterproof | Has O-ring seals to prevent moisture entering the interior. Some models can be submersible | Moisture should not be able to enter, but they are still at risk of fogging due to the air inside |
| Fog Proof | Filled with nitrogen or argon gas and sealed with O-rings | Prevents any moisture entering – no risk of fogging |
Will rain ruin binoculars?
It’s best to read the fine print. This explains exactly how resistant to moisture or water – or not – a pair of binoculars are.
Some models described as weatherproof or water-resistant might be okay in a light rain shower, but suffer if exposed to anything heavier. They may not be fog proof either.
Helpfully, there are scales available to measure how submersible a product is.
The German one is called DIN. DIN stands for Deutsches Institut für Normung, or German Institute for Standardization.
The Japanese one is called JIS – Japanese Industrial Standards. This is the one that is most commonly used by manufacturers to denote how watertight a pair of binoculars is.
How waterproof are waterproof binoculars?
JIS Waterproof Scale
- JIS Class 0: The device is not protected
- JIS Class 1: Device has protection against vertically falling water drops
- JIS Class 2: Protection against vertically falling water drops when enclosure is tilted up to 15%
- JIS Class 3: Protected against spraying water – Water sprayed at any angle up to 60º on either side of the vertical shall have no harmful effects
- JIS Class 4: Fully protected against splashing water
- JIS Class 5: Protected against water jets – Water projected in jets from any direction against the enclosure shall have no harmful effects.
- JIS Class 6: Watertight – Having no entry of water into inside by receiving direct jet of water from any direction.
- JIS Class 7: The device remains dry after temporary immersion in water
- JIS Class 8: The device remains dry during continuous immersion in water
Importantly, this waterproof scale does not describe a product’s resistance to submersion.
Rather, it is used to express how resistant a product is to different pressures and angles of spraying water, simulating what it might encounter in real life.
However, there are some binoculars that are described as being submersible to a specific depth and/or for a specified time. This makes them more resistant to leakage.
Are waterproof binoculars worth it?
When fog proof binoculars are sealed to keep the gas inside, they are equipped to deal with a wider range of weather. So this makes them waterproof as well.
Without risk of moisture inside, fog proof and waterproof binoculars are much more durable. They are resistant to dust, sand or salty air. Because they are waterproof, it makes them easier to rinse clean and dry carefully, when necessary.
Rinse off and wipe them thoroughly with a dry soft cloth. Do this rather than letting them dry off naturally. This is especially important to do immediately if waterproof binoculars get wet from salty or muddy water.
If they accidentally fall into water, they are more likely to survive and stay in top condition. This is great for people who want the best view possible in any environment or climate.
Advantages of waterproof and fogproof binoculars
Extended life
The internal optics are protected from corrosion-causing moisture
Higher quality viewing
There’s no danger of internal fogging spoiling your view
Better value in the long run
Because they last longer and maintain a better standard of image, they are worth the extra cost
More durable construction
They withstand wear and tear
Versatile
They can be taken into different environments without needing extra care
Peace of mind
The waterproofing and fog-proofing enable you to use them worry-free in poor weather or in places of increased humidity
In summary: are waterproof binoculars worth it?
It’s best to look for birding binoculars that are waterproof, even if you live in a climate where rain or mist is less frequent.
A fully sealed interior not only prevents the moisture that is always present in the air from entering but also ensures your instrument is protected from accidental spillages.
Look for the best waterproof and fog proof bird watching binoculars that you can afford to buy. This will offer you more opportunity to have a clear, mist-free view of all those wonderful creatures waiting to be spotted.
What birds do in wet weather: is bird watching in the rain worth it?
Everything you need to know about using binoculars in the rain
Contents
- 1 Why do my binoculars fog up?
- 2 Can I defog or fix cloudy binoculars?
- 3 How do I keep my binoculars from fogging up?
- 4 Do you need waterproof binoculars?
- 5 What does fog proof mean?
- 6 The best anti-fog treatment for binoculars: How do you fog proof binoculars?
- 7 Can binoculars get wet?
- 8 Are waterproof binoculars worth it?
- 9 Advantages of waterproof and fogproof binoculars
- 10 In summary: are waterproof binoculars worth it?