When we decide on a binocular, one aspect we have to consider is that it is an instrument for outdoors. It means, that in a place like mine where there is hot humid weather for three months followed by rains for about six months, and then wind and dust for another three, the binocular will need protection against the elements and whatever else we chose to throw at it.
Except the most inexpensive binoculars, most binoculars have some sort of weather protection and that is usually mentioned on the box. You have to read all the small print to know how capable or incapable your binocular is.
There will be terms like water resistant, waterproof, dust proof and fog proof depending on how good the quality of your binocular is.
Water resistant binoculars are the ones with basic weather protection. They are sealed but not as strongly as a waterproof one. They can probably withstand a light to heavy shower but a fall in the water will be the end of the road for it. Even if you avoid taking it out in the rain the humidity in the air can enter and ruin your optics, and if dust enters it will coat your lenses and block a clear view. Therefore, if you live in a place where heavy rain is very frequent it is better to avoid 'weather proof' or 'water resistant' binoculars.
Waterproof binoculars have O-ring seals on all possible openings where water can potentially enter which means besides keeping out water, they are also capable of keeping out dust and moisture. Even then ensure that your binocular is 100% waterproof. Otherwise they may withstand a heavy shower but a dunking in deep water may test its ability.
Fog proof binoculars are the norm these days and all the reputed manufactures will mark their products as 'waterproof and fog proof' or 'nitrogen-purged'. During assembling the instrument the atmospheric air is sucked out a replaced by nitrogen or argon and sometimes krypton, at pressures higher than normal atmospheric pressure. This higher pressure prevents moisture from re-entering the instrument. In addition, since nitrogen being anhydrous, no moisture condensation will happen on the lens surfaces inside it, even in cold weather. However, that won't prevent fogging on the outer surface of the objective or ocular lenses, like how our spectacles fog over when we get out of an air conditioned environment into warm and humid atmosphere.
Other than nitrogen, argon is used also by some manufactures for the same purpose. Argon being a heavier molecule is less likely to leak than nitrogen after a fall or knock. It is also inert so there is less chance of it reacting with the materials in the binocular. Vortex uses both nitrogen and argon in their binoculars. The less expensive line Vanquish, Raptor, Fury and Crossfire series are nitrogen filled, and their costlier models, Diamondback, Kaibab, Viper, Vulture and the top of the line Razor series are Argon filled.
These nitrogen or argon filled binoculars will see years of trouble free service as long as you don't cause damage to the O-rings. So when you buy your binocular for use in a place with prolonged or unpredictable wet weather, a binocular which says it is waterproof and fog-proof will give you peace of mind.
Many binoculars are rubber armoured or coated. In addition to contributing to the waterproofing they also protect the instrument from small bumps and falls.
For those who are impatient to
go through the entire blog series, I'm giving below direct links to all
the posts. You can go directly to the page you are interested in,
though I suggest you go through each post as all of them contain some
information that will be useful when you consider purchasing a binocular
for your self.
1. Introduction
2. Part – 1: Anatomy of a Binocular
3. Part – 2: Purpose and Portability
4. Part – 3: Magnification, Objective diameter & FOV
5. Part – 4: Eye Relief
6. Part – 5: Exit pupil & Interpupillary distance
7. Part – 6: Image brightness
8. Part – 7: Focusing fundamentals
9. Part – 8: Weather sealing
10. Part – 9: Purchase decision
11. Part – 10: Care & Storage
12. Afterthoughts and accessories
1. Introduction
2. Part – 1: Anatomy of a Binocular
3. Part – 2: Purpose and Portability
4. Part – 3: Magnification, Objective diameter & FOV
5. Part – 4: Eye Relief
6. Part – 5: Exit pupil & Interpupillary distance
7. Part – 6: Image brightness
8. Part – 7: Focusing fundamentals
9. Part – 8: Weather sealing
10. Part – 9: Purchase decision
11. Part – 10: Care & Storage
12. Afterthoughts and accessories
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