An overview of binoculars, their parameters, and areas of application
In childhood, an instrument like binoculars is often firmly associated with the sea, adventures, and the bravery of intrepid captains—surrounded by an aura of romance and exploration. However, in the adult world, the purpose of binoculars expands greatly, resulting in a vast variety of models tailored to specific needs.
A binocular, in essence, is a device designed to observe distant objects with both eyes simultaneously using two visual tubes. Unlike a monocular telescope, which serves a similar function, binoculars provide a full stereoscopic image.
Parameters and Characteristics of Modern Binoculars
As mentioned earlier, binoculars can simply be described as two tubes combined to magnify images. However, if you’re taking the task of choosing binoculars seriously, several parameters require close attention as they play an essential role in the functionality of this optical instrument. Let us delve deeper into these aspects.
Prisms
Prisms are responsible for forming the image. The prism system in binoculars can be of two types: the classic Porro prism and the roof prism system.
The structure of binocular prisms
Porro prism binoculars are easily recognizable—they have a design where the tubes form two cones with offset parallel axes. The distance between objectives (front lenses) is greater than the distance between eyepieces. Such binoculars might appear bulkier but provide better image quality compared to models with roof prisms.
The second type, the roof prism system, aligns both the objectives and eyepieces along the same optical axis. This design makes the device more compact, though sometimes at the expense of image quality or requiring a higher price point.
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Binocular Magnification
The magnification level shows how much closer the observed object appears compared to the real world. Standard binoculars usually have magnification up to 8–10x. At this level, the object remains stable, making it easy to observe.
At magnifications greater than 10x, using binoculars handheld becomes more challenging. High sensitivity makes any hand tremors distort the image.
These models are best used with a tripod or sturdy support. Additionally, due to their weight, size, and cost, they are less practical for everyday use. For general field observations, a magnification range of 6–8x is typically sufficient.
Some binoculars feature variable magnification, similar to the zoom function on cameras or camcorders. This parameter is often indicated in the model name using the term zoom—denoting variable magnification. The magnification range is then specified, such as 8–24, where the first number represents the minimum magnification and the second, the maximum.
Objective Lens Diameter
This parameter determines the brightness of the image, or light-gathering ability of the binoculars. The larger the diameter, the more light the lens can collect. This feature is especially relevant for those planning to use binoculars in twilight or nighttime conditions.
The diameter of the objective lens is typically indicated on the binocular model right after the magnification, separated by an “x.” For example, binoculars labeled as 8x40 have a fixed 8x magnification and a 40mm objective lens diameter.
Exit Pupil Diameter
Hunting Binoculars
Another important parameter when selecting binoculars is the diameter of the light beam that directly enters the observer’s pupil. Its value is calculated as the ratio of the objective lens diameter to the magnification. Therefore, with varying magnifications and the same objective lens diameter, binoculars can produce images with completely different brightness levels.
During daytime, when the human pupil is constricted, binoculars with an exit pupil diameter of around 2.5 mm are sufficient for obtaining bright and detailed images. For evening observations, when the pupils tend to dilate due to the dark, this parameter should be higher.
However, it’s important to remember that the pupils of a healthy person expand to a maximum of 7 mm. Hence, binoculars with a larger exit pupil diameter will be ineffective in this regard — the eye simply cannot perceive any difference in the image.
The Brightness of Binoculars is closely related to the previous parameters. Its value determines the brightness level the eye perceives at the binocular’s output, as the image loses some of its actual brightness when passing through the optics. Brightness is calculated as the square of the exit pupil diameter.
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Focusing System
This is another parameter that affects image quality. It’s necessary since human vision is unique and requires adjusting the optical device accordingly. There are binoculars with central and individual focusing systems. The first type is equipped with a single adjustment wheel for both barrels, whereas in individual focusing, each barrel is adjusted separately for each eye.
Individual focusing is particularly helpful for people wearing glasses with lenses of different optical strengths.
Durability and Waterproofing
Apart from the core technical characteristics of binoculars, the quality of their construction is crucial. These parameters are very significant because binoculars are often used in extreme conditions — during hunting, fishing, hiking, and travels. Thus, binoculars should be capable of withstanding drops, impacts, and shocks.
Steiner Skipper 7x50 K Binocular with Integrated Compass
Its surface should be made of special materials to ensure the binoculars do not slip out of hand during use.
It’s worth highlighting waterproof binoculars separately. They are more reliable not only for sea voyages but also in rain, when exposed to condensation, or accidental moisture. High-quality binoculars are also equipped with “dry” nitrogen or argon filling inside the casing to prevent lens fogging during sudden temperature changes.
Depending on how these characteristics are combined, binoculars are classified based on their application areas, which should also guide your choice when selecting such a device.
Types of Binoculars
Modern binoculars, depending on their functional designation, are divided into the following types:
Astronomical Binoculars are designed for observing not just terrestrial objects but also celestial bodies. Their distinguishing feature is significant weight, making it difficult to use such equipment without a tripod. However, they can fully replace a telescope, as their magnification exceeds 15x.
Marine Binoculars — nearly all models of this type come with nitrogen or argon filling, a waterproof casing made of non-sinking materials. Their magnification usually ranges from 7x to 10x, and they often include additional features like a compass and individual focusing.
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Military Binoculars are designed for use in harsh conditions, so they are rugged, waterproof, and often have built-in illumination. Various models come in different sizes, but they rarely have high magnification — it’s not needed in field military settings. These binoculars are a great option for professional soldiers, airsoft enthusiasts, hunters, and fishers.
Minox BN 7x50 DCM Binocular with Built-in Rangefinder
Special Hunting Binoculars often combine the best features of military and marine models. After all, hunting involves temperature fluctuations, humidity, and challenging environments. That’s why hunting binoculars are often constructed from duralumin or aluminum, rubber-coated, and filled with argon to prevent internal fogging.Tourist binoculars focus primarily on compactness—after all, when packing a hiking backpack, every gram counts. These models are most often made of plastic, weigh up to 500 grams, and are covered with a rubber protective coating. They are not “long-range”—the maximum magnification of such models is 8x.
Compact binoculars are a separate type of optics for observation. These models may have a magnification ranging from 4x to 14x, predominantly use the roof system, and are utilized in sports competitions, birdwatching, traveling, auto and moto shows. Thanks to their technical characteristics and lightweight design, they can also make an excellent gift for a child.
Night binoculars are usually quite large. They weigh over 1 kilogram and are equipped with a tripod. They are most often used for night fishing and hunting.
As seen from the above descriptions, binoculars offer an incredible variety. Each year, the market is enriched with new models featuring improved optics, protection, and design. In this broad spectrum of options, everyone can find their preferred model, matched to their needs based on specific parameters.
Thus, when you have a clear understanding of what you need binoculars for, choosing the right pair becomes much easier—whether for yourself or as a gift for a hunter, traveler, fisher, or simply a curious individual.
