For the most part, binoculars are essentially two small telescopes placed side by side consisting of a pair of lenses to bring distant objects closer into view. Binoculars can be used for bird watching, hunting, astronomy, or even inspecting the action at sporting events and concerts. A minor issue would be how to choose binoculars as choosing the right pair makes all the difference between experimental usage and guided usage. Shopping around for binoculars lets you discover a range of instruments that look alike but are priced differently and offer different performance levels.
You obviously don’t want to pay more than necessary for a good set of binoculars, but neither do you want to “save” and end up with a set of binoculars that makes you look confused. Understanding the specs of the various sets of binoculars and evaluating your needs and planned usage helps you in making the best purchase decisions. This basic guide about how to choose binoculars looks at the various important elements you’ll need to consider before making that final payment for your set.
When referring to the size of your pair of binoculars, you will be thinking about how small or large your set of binoculars is, of course. However, it goes beyond this, or more specifically, the overall size is directly attributable to the lens sizes. Larger binoculars tend to have more powerful lenses, while the reverse is true for smaller sets. You’ll come across numbers used to describe a set of binoculars. These numbers are the basics of the set of binoculars and can basically give you an idea of how well they help you see. Below is a detailed look at the typical numbers and how they relate to your binoculars.
- Full-Size (common specs: 10 x 50): These numbers are normally attributable to large sets of binoculars. The first digit in the description indicates the magnification offered by the set, which means the object being viewed will be 10 times closer through the binoculars than it would appear to the naked eye. The second number gives you the size of the objective lens in millimeters, which translates to the amount of light entering the binoculars. Full-size binoculars are good for lower light conditions, as they are able to gather more light due to their larger objective lenses.
- Mid-Size (common specs: 10 x 32): The mid-size set of binoculars will offer a different experience compared to the full-size binoculars set. The magnification will be the same if the first digits are similar to those on the full-size binoculars. The second digits tell you that the objective lens size is 32mm and thus this pair will gather relatively less light compared to larger sizes, so it won’t perform as well in lower light conditions.
- Compact (common specs: 10 x 25): The compact series of binoculars are small and are very easy to carry around, easily fitting into your pockets or enabling you to carry them around without being too conspicuous. While you will be able to enjoy good magnification, the lower objective lens sizes will limit the brightness of your images due to the smaller size. This will also limit your field of view.
The size of your binoculars is dependent on the size of the objective lens. The larger the lens, the larger the size of your set is. The larger objective lens also affects the weight of the binoculars, as larger objective lenses lead to relatively heavier pairs that are harder to carry around.
Before we proceed in some of the key aspects that we should take into consideration in looking for the best and most fitted binoculars, here is a video that also shares almost the same concept and idea:
As you can see, the first thing you need to take into account is the binocular size. Other things would be irrelevant if you cannot fit the binoculars to your hand, grip and vision.
The brightness of the image produced by the binoculars is affected mainly by the size of the objective lens. The difference in image brightness might not be discernable in conditions of good lighting, but it becomes more apparent when you move to areas with less bright light. The objective light consideration is a good way to look at image brightness, but a more advanced way to look at the brightness offered by your binoculars is by using the exit pupil measurement. This is a number that indicates how bright an object appears when viewed in low light conditions. A higher number translates to brighter images.
You can figure out the exit pupil size by dividing the diameter of the objective lenses by the magnification number:
- For a 10 x 25 set of binoculars, 25 divided by 10 equals an exit pupil diameter of 2.5mm
- For a 10 x 50 set of binoculars, 50 divided by 10 equals an exit pupil diameter of 5mm.
From these examples, it is clear that you will enjoy brighter images from the 10 x 50 set of binoculars. When light conditions are poor, your pupils can widen to between 6.3–7.2 mm. If your choice of binoculars offers an exit pupil size much lower than these numbers, it will restrict the amount of light your eyes are receiving. Higher exit pupil size translates to brighter images and should be highly considered if you intend to use your set in low light conditions, such as for stargazing or in forested areas.
The distance between each eyepiece and your eyes with the whole field of view being visible is referred to as eye relief. For comfortable usage of your binoculars, you’ll want greater eye relief, which will allow you to hold your set away from your face. Eye relief is quite important for users who wear glasses. If you wear glasses, you should consider a pair with higher eye relief to see more things through your binoculars.
Binocular Field of View
This tells you the width of the area that you will be able to view at a glance through the binoculars from where you stand. A wide field of view is best to find and identify objects such as wildlife or things scattered in a wide area. The higher the magnification used, the lower the field of view you can enjoy.
Most binoculars have a central focusing wheel that focuses both barrels on the binoculars at the same time. Appreciating that each eye might have a different viewing ability, a diopter adjustment ring helps you refine the focus on each barrel separately. This helps in giving you refined viewing by focusing one barrel independently of the other.
Coatings prevent reflection and scattering of light. This is important in minimizing light loss and also guaranteeing the best image contrast to more clearly see what you’re looking for. Multiple layers of different anti-reflection coatings (multi-coating) can reduce loss to as low as 0.25 percent, providing quality light transmission and higher image contrast.
Depending on the conditions in which you expect to use your set of binoculars, it is important to consider their weatherproofing abilities. Waterproof binoculars prevent moisture from getting into the lenses and also prevent dust particles from finding their way into your set. The ultimate outdoorsy individual will want a waterproof set of binoculars, enabling him or her get maximum utility of the set during activities such as hunting, fishing, or birding.
When moving from different climate zones or temperature zones, fogging up may occur on your set of binoculars. Fog has the potential to lead to astronomical levels of frustration for you when trying to see through the lenses, but the ultimate result is damage to your set of binoculars. A good set of binoculars should be protected from fogging to ensure that you can comfortably switch locations and temperatures without any inconvenience.
With all these different facets in mind, you have a clear idea of what all those terms and numbers mean when you go to look at different binoculars. Keep this information—and your intended use or hobby—in mind as you start to shop for your perfect pair.