After you expose a pair of binoculars to a great difference of temperature, (e.g. from cold outdoors to hot indoors – reaching dew point), in a very humid environment or even using them on a rainy day, binocular lenses are usually get fogged up (same as glasses) creating a layer of condensation on the lenses, however, on most of the binoculars, this happens only on the outer side of the front lenses or eyepieces.
Rarely, in the case, the binoculars are not waterproof, weatherproof, and fog proof (lack of dry nitrogen gas and not perfectly sealed), condensation can form inside the binoculars.
Condensation inside the binoculars is bad. Not only that you will have a hard time to watch through binoculars if those are fogged-up, but this exposes the binoculars to the risk where fungus can grow inside, permanently damaging the quality of the binoculars.
How to remove internal binocular condensation? The best way to remove internal condensation is to store the binoculars in a tight bag with a few pouches of silica gel (desiccant) in a place with low humidity for a couple of days. The desiccant will absorb the condensation from inside the binoculars.
Alongside various reason this happens, what are the risks, and what can we do to prevent it, temporarily or permanently? What to do in the worst-case scenario? I want to explore these topics in order to cover everything is to know about internal binoculars condensation and what can you further do.
The amount of condensation inside the binoculars
As mentioned above, when you expose the binoculars at a great temperature difference (past dew point in which terms, condensation forms) or in an environment which your binoculars are not supposed to work under (rain, water, humid etc.), the glass lenses get foggy, aka blurry. For sure, you are not able to see through the binoculars at this time.
However, when the binoculars are repeatedly exposed to a specific environment where condensation can happen, and in your binoculars instance, those fog inside doesn’t dry up, this may further condensate into tiny water drops. It shouldn’t be a problem on the outer side of the lenses, of course, but it’s a problem when this happens inside.
Of course, most will evaporate. However, when this fogs more often inside with the inability to evaporate or when you use the binoculars in a very humid environment, condensation continues to form where a minimal amount of water may temporarily remain present inside the binoculars.
In this case, due to the presence of oxygen, the fungus can grow inside. That is a great deal, as the only way to remove fungus is to open up the binoculars and clean them in a perfect dust-free and humid-free environment. It could be a complicated process, depending on the type of binoculars, and in most cases, this cannot be done at home.
This is why is crucial to remove all the humidity from inside the binoculars before this happens.
How this will affect the quality of the binoculars?
If your binoculars are not totally sealed and fogging/condensation happens inside, be sure that at least when the binoculars are fogged up, you won’t be able to use them, where in the case of condensation, it can happen exactly as specified above.
Normally, if this happens one time, you shouldn’t be worried too much. The amount of humidity inside your binoculars shouldn’t be too high. However, keep in mind that if this happened once, it could happen again, and your binoculars may not be completely sealed.
How do you notice the fogging happened inside the binoculars? That would be a straight forward answer because if you wipe both the ocular eyepiece lens and the front glass and still see fogging, it is inside. It could be just on the inner side of the lens, on the prisms or other inside lenses, depending on your binoculars model.
Also, there is another thing I want to mention, in special to older binoculars, where the body is made of metal, this can create a layer of rust (in time) inside the binoculars. I don’t have to tell you how bad it is to have rust inside the binoculars. However, if your binoculars are made of metal and nitrogen-purged, there shouldn’t be any risk of forming rust (cannot confirm nor deny in the long term)
Removing the fogging and condensation inside the binoculars
In this subsection, I want to explore with you the three ways you may be able to remove the condensation from inside the binoculars, depending on the amount.
- The first scenario would be storing the binoculars overnight or even over a couple of days in a very dry and warm place. The water particles from inside the binoculars will start to evaporate again. If you do that, you may notice tiny water drops on the inner side of the binocular lenses, which can also happen on the prisms (they are made of glass).
Please keep in mind that if water drops are formed inside the binocular lenses, there is no guarantee in this case that after evaporating, the inside of the binoculars will completely dry up. There is even a risk where the water drops will leave dirty spots on the inner side of the glass or prisms. Although this is an option, I would not recommend it only if you don’t have any other choice and at your own risk (to avoid spots).
- In the second scenario, I want to underline what I said in the answer paragraph: Using a couple of small silica gel bags (desiccant) and placing them in a sealed bag altogether with the binoculars. The silica gel purpose is to absorb humidity, and that why this is often used in storing items for a long-term period of time. This is the safest and best way to remove the condensation from inside your binoculars.
The desiccant is not expensive to buy. You can find it on Amazon, eBay or any other large markets, or even to your corner shop (unlikely). Likely, you may even have it in your house, as this often comes with electronic devices, shoes and many house-hold items. Please refer to the cautions referred to on the silica gel bag.
- If there is actually a larger amount of water inside your binoculars, neither storing them in a dry and hot environment nor silica gel would help. There is no much you can do other than to take them to a specialised shop to remove the water from inside the binoculars if you cannot do it by yourself.
Remember that depending on the type of binoculars, it could be either straightforward to do it yourself (unscrew the front elements) or complicated as everything is sealed off. I would not recommend you to do it by yourself unless you know what you are doing, as there is a risk of permanently damaging your binoculars or decalibrating them.
How to prevent condensation inside the binoculars.
What types of binoculars do you have? The first step is to identify your binoculars and if this is waterproof, weatherproof and dust-proof. Normally, nitrogen-purged binoculars are all of the above and more. I will give you a quick example; my Nikon Prostaff 10×42 binoculars (internal link) checks all of the above points.
If your binoculars are pretty much similar, your manufacturer guarantees that you may be able to use your binoculars under harsh weather conditions. I used mine during the winter, stormy weather, fog, day and night, during hot and freezing weather. They are excellent (as they are supposed to be) with no issues at all.
But what if your binoculars don’t meet the above specs? First time, think about storing them in a dry place with under 60% humidity, then consider limiting their usage in humid environments as there would always be a risk involved. As to prevent condensation inside the binoculars, you have to prevent condensation on your binoculars at all. In this case, if your binoculars foggs up on the outer lens, there is a chance it may happen inside. The main tip is to try to avoid the dew point.
Even when storing them into their own carry bag in your room, drop a bag or two of silica gel inside to keep the inside of the carry bag with very low humidity.
I strongly recommend you to follow our other post, “how to prevent binoculars from fogging up (internal link)” – This would be perfect for covering both inside and outside of the binocular lenses. Just a quick tip, it is all about to control the temperature of the binoculars when going from hot indoors to cold outdoors and vice-versa.
There’s fungus inside my binoculars because of frequently fogging. What should I do?
If you stored your binoculars for a very long period of time in an inadequate humid place with differences of temperature between day and night (e.g. in a garage) and your binoculars are not completely air-tight (referring to the above scenario), with the frequent presence of humidity and oxygen inside of the binoculars, the fungus may grow.
This often reflects in special to older types of binoculars gen. WWII, cheaper binoculars, indoors ones, damaged or bad manufactured.
There is no much you can do if the fungus is present inside the binoculars. You have to take them to a specialised shop and repair them for a price. Now think if your binoculars worth repairing and their value. If it does, go for it. If not, it would be your decision.
Take good care of your binoculars and ensure that you store them safely for a longer period of time if they are at risk of getting condensation inside. If you don’t own a pair of binoculars yet and you are looking to buy one, ensure that you are going to chose a model which is weatherproof, waterproof, fog-proof, dust-proof, “all-proof”, filled with nitrogen-purged gas. These models won’t create any condensation inside, no matter where and how you use them.
Thank you for remaining with us until the end of this post. I hope you found your answer and this article was informative enough. I wish you have a good day and hope to see you around. Take care.