Which binoculars should I choose?

Binoculars are a nice tool for many types of activities – bird watching, hiking and general outdoor life when you want to look at animals and nature up close. Before you buy binoculars, it can be good to think about what is important to you. Do you want a spotting scope or hand-held binoculars? When should you use the binoculars? And how much should they weigh? In this guide, we explain the various concepts that occur and give you advice on what to consider when buying binoculars.

Different types of binoculars

Hand-heald binoculars

A pair of hand-held binoculars is a good and stable type of binoculars for looking at birds, animals and nature. Binoculars are popular in bird watching and are also suitable at dawn and dusk.

Compact binoculars/mini binoculars

Compact binoculars, also called mini binoculars, are both smaller and lighter than handheld binoculars, which makes them easy to carry in your bag or pocket.

Spotting scopes

Spotting scopes are larger in size than both hand binoculars and compact binoculars and require a tripod to be able to focus, provide more detailed images and to counteract shaky images. With a spotting scope you are usually stationed in the same place, for example when bird watching.

Magnification, light and aperture

Binoculars are often named with a numerical specification, for example "8x42". The first number represents how much magnification the binoculars have. In this example, the magnification is eight times, which can easily be explained that an object is perceived to be eight times closer. The second number represents how large the objective diameter is, i.e. the lens size. In the example, the glass lens is 42 mm. The size of the glass lens affects how much light is allowed in. The larger the lens diameter, the brighter and better the image.

Hand-held binoculars are usually very bright and come with a magnification between 7x–12x and a lens diameter of at least 40 mm. Compact binoculars usually have slightly lower light sensitivity and a smaller field of view than handheld binoculars. The most common is a magnification of 8x with a lens diameter of 30–32 mm, which means that they fulfill their function in most weather conditions, but are at their best in brighter weather. For spotting scopes, magnification and front lens are significantly larger. If a binocular has greater magnification than 12x, a tripod is a must, otherwise it can be too shaky to see details clearly.

Keep in mind that binoculars with a larger objective diameter result in larger and heavier binoculars, so think about what is most important to you before choosing binoculars. Another important thing that can affect the light admission is the quality and surface treatment of the glass lens, this can determine the difference between cheap and expensive binoculars.

Porro prism or roof edge prism?

The construction of binoculars can most easily be divided into two different prisms – porro prism and roof edge prism. Prisms decide how the glass is angled in the binoculars. The most common and oldest construction is porro prism.

Porro prism

Porro prisms are cheaper and easier to manufacture, but still provide good function and optical quality. These types of binoculars are wider and heavier compared to roof edge prism binoculars, making them a better and cheaper option when size and weight are not critical.

Roof edge prism

Unlike porro prisms, roof edge prism binoculars have a streamlined design that makes the binoculars more compact and lighter. This makes it more attractive when size matters, for example in bird watching. The streamlined design also offers other benefits; it allows you to hold the binoculars with your arms closer to your body, which provides a more stable picture and makes it more resistant to shakes.

One of the disadvantages of roof edge prisms is the brightness. Binoculars with roof edge prism do not have nearly as good brightness as binoculars with porro prism, therefore binoculars with roof edge prism are more dependent on high quality as well as surface treatments on the glass lens – which also makes it more expensive.

BAK-4 or BK-7?

BaK-4 (barium crown glass) and BK-7 (borosilicate glass) are two different glass coatings on prisms that refract the light in the binoculars. Bak-4 is of better glass quality and has a higher refractive index which results in higher image quality, clearer image and smoother sharpness, compared to a prism unit of the same type with BK-7 glass. A BK-7 is often defined by its exit pupil not being perfectly round, which causes you to experience clarity problems at the edges of the image.

Binocular functions and features

Near limit: indicates the shortest distance at which you can view an object but still be able to have full focus and be able to see the object clearly. The near limit is an important detail if you are going to use the binoculars to view closer things.

Eye distance: relationship from the eye to the lens. This distance can vary from model to model but is generally between 10–20 mm. If you wear glasses, we recommend a distance of at least 14 mm. On many models, this can be set using rotating eyecups, alternatively eyecups that can be folded down.

Exit pupil: indicates how much light passes through the binoculars to the eye. At dawn or dusk, we recommend a value of 5 mm or higher and in daylight a value of 2–3 mm.

Field of view: specified either in meters at a distance of 1000 meters or in degrees. This indicates the width of your field of view when looking at something through the binoculars. In general, binoculars with increased magnification have a reduced field of view.

Diopter adjustment: is a setting to adjust the binoculars to suit your vision. The different visual acuities of the eyes are equalized with the help of a focus wheel, the focus wheel is usually placed under the right eyeball.

Anti-reflective treatment: is a coating used on the lens glass that prevents light from being reflected away, which means that the binoculars get much better light penetration and that the image quality is increased.

Optical quality: many binoculars with longer lens systems, for example binoculars, have a treatment against chromatic aberration. This treatment helps to correct color defects that occur. This treatment can go by a number of different names, such as HD, ED, APO and fluorite.

The twilight factor: a value of how effective the light transmission of the binoculars is when used in poorer lighting conditions, for example at dawn or dusk. A higher value gives a clearer and more contrast-rich image.

Gas filled binoculars: are binoculars filled with some type of gas; nitrogen gas or argon gas. These can also withstand high water pressure. Binoculars that are filled with gas also offer the advantage that fog or moisture does not form on the inside of the binoculars, plus dust does not get in as easily.