How To Work Out Binocular Magnification? Find Out Here!

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Updated on: 

October 6, 2021

Binocular Magnification - How To Calculate It?

The most important purpose of binoculars is to help us magnify an image which we couldn't see with detail from a distance.

To work out the magnification of binoculars, you simply divide the objective focal length of your binocular by the focal length of the eyepiece on your model. 

Magnification on a binocular refers to how many times closer you can see an object than without the binoculars and can differ from 10x-60x.

So, to make it a little clearer, we have put together a step by step guide below to help you work out your binocular magnification.

Calculating Your Binocular Magnification

To calculate your binocular magnification you simply need to divide your objective focal length and eyepiece focal length.

We have listed out a few steps below to get you started.

  • First, check your magnification and objective lens diameter on your model, this will be written in an x number such as 10x50.
  • Then find the focal length of your bincoulars objective tube which can typically be found in the guide of your model.
  • After this, you should then find the length of your bincoulars focal length eyepiece.
  • Divide the focal length of the objective tube on your binocular by the focal length of the eyepiece. For example, a 240mm objective focal length divided by a 24mm focal length of the eyepiece on your binocular would calculate an 8x magnification.

How Does The Magnification Work On a Binocular?

Magnification on binocular works through the objective lens and the eyepiece on a binocular.

This objective lens on a binocular collects light and helps you focus on a subject, the wider the aperture of your objective lens, the more light that is shown in your image.

For viewing the image closer, the eyepiece on your binocular helps to magnify the distant object when you look through.

Magnification can be controlled with different focal lengths but is affected in quality by external factors such as lens coatings and brightness.

The x number on your model related to how many times the closer the image is shown to you through your binoculars.

For example, if a bird is 50 yards away from you and you are viewing it through a magnification of 8x then you would see the bird as only being 6.2 yards away from you.

Which Magnification Is Better 8x or 10x?

The most common magnification in binoculars is between 8x and 10x, making it hard to determine which level of magnification is right for you and your use.

Most beginners gravitate towards 10x binoculars as they think a higher magnification will be the best, but this is not always the case, and each type of magnification has its pros and cons.

10x Magnification

10x magnification comes with many advantages, for example, this higher magnification allows you to view subjects from very far away, making it ideal for hunting or star gazing.

These binoculars are the perfect option if you care less about the field of view and want a magnified detailed view of your subject.

Disadvantages of 10x magnification have to be the smaller field of view which is not suitable for moving objects, this is caused by the higher magnification.

The high magnification also means that the image will be shakier during use as its zoomed-in 10x more in real life, making it susceptible to showing any external movement in the image.


  • Great for safaris and astronomy.
  • Gives a 10x magnified detailed view.
  • Can be used with a tripod.


  • Hard to hold steady with shaky movements visible.
  • A smaller field of view.
  • Heavy and expensive.

8x Magnification

8x magnification is very suited for hobbies such as birdwatching and does not compromise on the field of view, which makes them great for studying and keeping track of moving animals or subjects such as sport.

They are also much more suited for narrow places such as woods and can come in lighter weights than 10x models.

Drawbacks of 8x magnification have to be their lack of magnification for situations such as astronomy and safari. These models also might be harder to use in wider terrain situations.


  • A good field of view.
  • Affordable.
  • Lightweight & great for narrow areas.


  • Lack of magnification.
  • Not suited to wide terrains.

Overall, there is no wrong or right when it comes to magnification, a 10x model will be great if your planning on looking at subjects from a greater distance and 8x model is still an excellent option if you are looking for a wide field of view too.

What Is The Strongest Magnification You Can Get On Binoculars?

The most powerful magnification you can get on binoculars is up to 160x on some of the most top professional astronomical models.

However, typically on the market, you will find a range from 3x to 60x magnification power available. For most general use a magnification of 8x 10x and 12x is the best.

Best Magnification For Different Types Of Viewing

If you are still confused about whether you need a high or low magnification on your binocular after calculating, we have listed out some common activities performed with binoculars below and their ideal magnification level required for you to get the best sight possible when observing.

  • Theatres - A low magnification level is required for concerts and theatres due to the proximity you are using the binoculars in to observe. For this type of activity, we recommend a magnification of between 3x and 5x.
  • Sporting - For sporting, you want a medium amount of magnification, with a large field of view and lightweight due to holding the binoculars for long periods. Levels of 6x 7x or 8x should be ideal for sporting.
  • Birding - When birding with your binoculars your model should have a magnification 8x or 10x. 8x is perfect for birds as still gives a wide field of view and 10x is great for hunting.
  • Hiking - Any magnification level of 10x, 12x and 15x is suitable for travelling as you don't require a wide field of view in this situation.
  • Astronomy - For astronomy, at a hobby level your binoculars need to have a good magnification of at least 20x. This type of magnification can allow you to see the moon and planets in much greater detail.

Frequently Asked Questions About Binocular Magnification

What type of magnification do I need for viewing constellations?

For professional astronomical purposes, your binoculars need to have a magnification of 40x, 50x, 60x or even 90x.

These models will be much more expensive but allow you to see mars or even Saturn rings with ease in low light.

Is there a general best magnification?

For hobby use, we would recommend sticking with an 8x magnification or a 10x magnification as these models are affordable and still give a better field of view with more stability then magnification levels of 12x and over.

What is an ocular?

An ocular refers to the eyepiece where you look through and see your image magnified during observing.

Will magnification affect my field of view?

Yes, the higher your magnification then the smaller the field of view on your binoculars.

This can be a drawback in situations such as sport or birding as your subject will move often, making it harder to keep track of and follow with the binoculars you have.

Is it true my image will be shaky with a higher magnification?

Unfortunately, higher magnification will need more stability, this moving image is not only annoying but can mean you lose track of your subject easily.

What else affects the magnified image on a binocular?

Many other factors can affect how your magnified image looks on your binocular.

From coated optics to the objective lens diameter, or Porro prism/Roof prism binoculars, there are many features to consider apart from magnification in your model.

Born and raised in the south coast of UK, a small town close to Cornwall, I have adventure in my blood. Ever since a young age, I have always been into the great outdoors and particularly love watching the natural wildlife. Birdwatching is what I enjoy the most, and thus my natural interest in binoculars began. I founded and run Best-Binoculars.UK a site where I talk about various aspects of and review binoculars. Hope you enjoy my ramblings :)

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Born and raised in the south coast of UK, a small town close to Cornwall, I have adventure in my blood. Ever since a young age, I have always been into the great outdoors and particularly love watching the natural wildlife. Birdwatching is what I enjoy the most, and thus my natural interest in binoculars began. I founded and run Best-Binoculars.UK a site where I talk about various aspects of and review binoculars. Hope you enjoy my ramblings :)

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