If you’re in the market for a set of binoculars you might have noticed that many of them claim to be filled with nitrogen. Chances are, you’re also wondering why. Most people don’t think about their binocular lenses being filled with much of anything, not to mention nitrogen gas. However, there is a very good reason for this, and it’s all done quickly and simply in the factory.

It’s sometimes easy to get confused by the terminology that is used to describe nitrogen-filled binoculars. It’s also important to realize how many different terms are frequently used interchangeably. Lastly, you want to know how effective this method is and whether or not it exists with every set that is available for sale.


In a nutshell, it’s used for waterproofing purposes. It’s important to realize that you might buy a product that says it’s waterproof, water resistant, or even weather resistant. All of these terms are typically used interchangeably, and it almost always means that nitrogen gas has been used to create their resistance to moisture. Otherwise, it might become virtually impossible to see anything through lenses that have any condensation on them, especially in certain weather conditions.


Believe it or not, each lens’ compartment is flooded with gas, then held in with a valve that is typically hidden from the consumer. Since this is something that is done at the factory, the valve is left exposed until everything else has been assembled. Seals are put in place to assist with water resistance, and then the nitrogen gas is used to flood the compartments.

This process seals out any other moisture that might be present at that time and even prevents moisture from forming later. Once that has been accomplished, the valve is closed, and the exterior portion of the assembly is completed. Therefore, the consumer almost never sees the valve, yet it is indeed there in most cases.


This is where it becomes important that you don’t get hung up on terms. These two terms sound like polar opposites, but they mean exactly the same thing. Some companies use the term nitrogen-filled to indicate compartments that have been filled with nitrogen gas. Others use the term nitrogen-purged to denote that nitrogen gas is present in the compartments, thereby purging the moisture out of them. It’s easy for consumers to get confused here because it can easily sound like nitrogen is being used added in one term and purged out of the compartments in the other. However, they, in fact, mean the same thing.


Every once in a while, you’ll run into a situation where a particular set of binoculars has not been constructed utilizing this method. It’s extremely rare, especially with more modern products. The biggest chances you have of running into this scenario is if you’re looking for a set that costs next to nothing. Anything that’s well made is probably going to utilize this method. A good rule of thumb is to remember that in most cases, you do indeed get what you pay for. If you’re shelling out less than $100, there might be a reason for it. It’s important to remember that while you don’t want to spend money unnecessarily, you also want to get a product that you’ll be happy with for a long time. Therefore, it pays to do your homework before you spend anything.


This is an extremely effective technique that keeps moisture from collecting on your lens. With that being said, it’s probably not a good idea to deliberately test the theory by throwing your binoculars into the lake, but as long as you use them with some common sense, you shouldn’t experience any problems.

If you really want to be sure that you don’t have to deal with moisture issues later on down the road, make sure that whatever you decide to purchase has been filled with nitrogen. If you can’t find that information on the box, ask someone that knows about the products or do some research of your own online. It can help extend the life of the product you eventually choose to purchase.