What Do Numbers on Binoculars Mean? Complete Explanation!
Binoculars are absolutely necessary for bird watching, stargazing, hunting, and other outdoor activities. But what do the numbers on the binoculars mean?
Let’s take a closer look.
The first number (e.g. 8×42) indicates the binocular’s magnification power. This means that the image you see through binoculars is 8 times larger than it is with the human eye. The second number (e.g. 8×42) refers to the binocular’s “aperture” or “objective lens size.” This is the front lens size of the binoculars, expressed in millimeters. A binocular with a larger aperture will gather more light, making it better for low-light conditions like dawn or dusk.
The final number in the binoculars’ description (e.g. 8×42) is the “exit pupil.” The light beam that leaves the binoculars and enters your eye has a diameter of this size. A brighter image result from a relatively large exit pupil because more light is entering your eye.
So, This article aims to guide beginners about numbers on binoculars. Let’s begin!
What Do Numbers on Binoculars Mean – Infographic
Binocular Anatomy
When you pick up a pair of binoculars, you might not think about all the different parts that make them work. However, each component is essential for allowing you to see distant objects clearly. The objectives and oculars are the two main components of binoculars.
The objectives are the lenses in the front of the binoculars that collect light from the object being observed. This image is magnified and projected onto your retina by the oculars, also known as eyepieces.
Between the objectives and the oculars is a series of prisms that reflect and bend light in order to produce an upright image. Without these prisms, the image would appear upside down.
Finally, binoculars also have an adjustable focus knob that allows you to fine-tune the image based on your vision. By understanding the different parts of a pair of binoculars, you can appreciate how they help you to see distant objects more clearly.
Parts of Binoculars
1- Focus Ring:
The focus ring is located near the eyepieces and is used to change the focus of the binoculars. This allows the user to see the target from a long-range or close-up. The focus ring can be turned clockwise or counterclockwise. However, the amount of turn needed depends on the binoculars and the distance of the object.
Once the object is in focus, the binoculars can be moved closer or further away from the eyes to fine-tune the image.
2- Diopter Adjustment:
When looking through a binocular, you may notice that the focus wheel on different models is located in different locations. This is due to the fact that the focus wheel adjusts the diopter, which is a unit of measurement for a lens’s refractive power. You can make the focus smoother on your binoculars using the diopter adjustment.
By turning the focus wheel, you can change the distance at which the binocular is focused. This can be useful when trying to focus on something that is just out of reach.
For example, if you’re looking at a bird in a tree, you would use a higher diopter setting than if you were looking at a mountain in the distance. On most binoculars, the diopter adjustment is located near the right eyepiece.
However, some models place it near the left eyepiece, and some even have separate focus wheels for each eyepiece. It can also be useful for fine-tuning the focus when using a tripod-mounted binocular.
So, next time you’re using a binocular, take a look at the focus wheel and see how it works!
3- Tripod Adapter Connection
The tripod adapter connection is an important piece of equipment for long-distance binoculars. It allows the binoculars to be mounted on a tripod, which is necessary for stability when viewing distant objects.
Besides that, the tripod adapter provided me with the benefit of protecting my binoculars from damage by preventing them from being accidentally dropped during my previous hunt.
Understanding Numbers on Binoculars
1- Magnification
Binocular magnification indicates how many times the target picture has been magnified to make it clearer. Binocular magnifications serve distinct functions. This number on binoculars is a mixture of two figures, 8×42 and 7×35.
Here, 8x is the magnification power, and 42 is the objective lens diameter. Binoculars with 8x magnification show the image 8 times closer than what our naked eye can see.
The greater the magnification power = The Closer and clearer the object
The numbers help tell the user what the binoculars are good at viewing. Thus, some magnification powers of binoculars are below.
- Magnification for hunting, we recommend 7x to 10x magnification.
- Magnification for bird viewing, We recommend 8×42, 10×42, or 10×50 magnification.
- For low light hunting, we recommend 7×50, 8×42, or 10×50 magnification.
- For hiking and watching nature, we recommend 7×35, 10×42, and 10×50 magnification.
2- Objective Lens Diameter
The objective lens diameter is measured in mm (millimeters). If a binocular has an objective lens diameter of 8×42, it means it has a magnification of 8 and a lens size of 42mm.
Moreover, it is important to note that when you increase the power of binoculars, the view of the field decreases. The Lens diameter plays a crucial role in image quality.
Larger the lens, the brighter the image. As the diameter increases, the weight of the binoculars increases. We usually recommend 50 mm as it is suitable for the sites where users go for wildlife and bird watching and makes the binoculars easy to carry.
However, Lens diameters are more important for low light and night sky viewing conditions.
3- Field Of View (FOV)
The field of view refers to the area that one gets to see when looking through his binoculars. It is measured either in feet per 1000 yards or in meters per 1000 meters which is more briefly defined as the maximum area you get to see at 1000yards.
The FOVs in binoculars vary based on their magnification and objective lens. For example, a field of view of 400ft means that if you are looking at something 1000 meters away, the width of field you get to see would be 400ft.
As covered before, the field of view is inversely related to the magnification of a binocular. The smaller the magnification, the wider the field of you and the other way around. It will help if you consider how much magnification and FOV you require. However, the field of view is not expressed in degrees, but the angle can lead us to the field of view.
Suppose the angle of view of a binocular is 7.6 degrees. Now multiply the angle of view, which is 7.6 by 52.5. This gives us a 400ft field of view. Thus, a 7.6-degree angle of view is equal to 400ft FOV. You might be curious why we multiply the angle of view by 52.5. This is because 1 degree is equal to 52.5ft at 1000yards. view.
4- Eye Relief
Binocular eye relief is basically for those who wear glasses. It is the distance from our eyes to the eyecups. Moreover, those who wear glasses can relate that there is a distance between your naked eye and the binocular lens, and if this distance is removed, they can easily miss the target. Thus, glasses wearers should go for binoculars with an eye relief of 15 mm.
Check out our details blog on binoculars eye relief here!
5- Close Focus
The number of close focus on binoculars indicates the distance between the binocular and the closest object on which it can focus. Furthermore, it determines how easily a person can perceive an item with a clear focus.
6- Exit Pupil
The basic calculation for eye pupil number equates it to magnification divided by object lens diameter. It is the size of the dots that appear while focusing on the object.
Through these spots, lights enter your eyes and form a clear image of the object on your retina. In most conditions, the exit pupil number should be greater than 4 mm.
Hopefully, now you know about all the numbers on binoculars.
Numbers on Binoculars – Quick Checklist
- Magnification: Magnification power is the number of times the target’s picture has been magnified. Furthermore, the higher the magnification, the more visible the object.
- Lens Diameter: It tells how much light enters the lens. Similarly, a larger lens means better image quality.
- Field of View: The width of the area you can see with binoculars is known as the field of view. Mostly, high-quality binoculars have a field of view of 300-350 feet.
- Eye Relief: In binoculars, eye relief represents the distance from our eyes to the eyecups. Whereas binoculars with longer eye relief, i.e.15mm, are recommended for glasses wearers.
- Close Focus: The minimum distance between the binoculars and the nearest object you need to focus on using the binoculars is its close focus. However, it becomes more important when there is a need to magnify very close objects.
- Exit Pupil: It is calculated by dividing the magnification by the objective lens diameter and determining the picture’s brightness. For night seeing, for example, an exit pupil of greater than 4mm is advised.
Final Wording
In this article, we have briefly discussed the numbers on binoculars and their meaning. If we summarize what these numbers tell, it is how large and clear the image shown with the binoculars will be. Hopefully, this article will help you find the right pair of binoculars, using numbers and features you did not know before. Now it is up to you to pick a binocular that is best for you.
FAQs
1- Is 10×25 better, or is 10×50 good for viewing the night sky?
To answer this question, 10×50 is suggested, and the reason for this is that it will allow you to readily view faraway things in the sky. On the other hand, a larger lens diameter will provide a brighter and more precise observation.
2- What does 30×60 binoculars mean?
The first number (e.g. 30×60) indicates the binocular’s magnification power. This means that the image you see through the binoculars will be 30 times larger than it would be with the naked eye. The second number (e.g. 30×60) refers to the binocular’s “aperture” or “objective lens size.” This is the diameter of the binocular’s front lenses, measured in millimeters.
Conclusion – What Do The Numbers On Binoculars Mean?
In this article, we have discussed the details of important numbers related to binoculars. If we summarize what these numbers tell, it is how large and clear the image shown with the binoculars will be. Hopefully, this article will help you find the right pair of binoculars, using numbers and features you did not know before. Now it is up to you to pick a binocular that is best for you.
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