What Is The Meaning Of Binocular's Numbers?

If you are new to the binocular world, all the numbers and sizes for different models can become confusing.

To make it simple for you, the two numbers you will see on your binoculars refer to the magnification and objective lens size of your model. 

You may also come across some other numbers for your binocular referring to features such as field of view or the exit pupil of your model.

We have put together a fool-proof guide below to help your figure out what all these numbers mean.

What Is Magnification?

The first two main numbers you will see on your binoculars are the magnification and objective lens size.

The number at the start refers to the magnification your model can produce such as 8x42 or 7x32 and the magnification means how many times closer your image will appear to your pupil, so a 10x50 pair of binoculars will produce an image which is ten times closer to you.

Higher magnification will need a stabiliser such as a tripod, but for subjects less than 3km away a magnification of under 10x should be sufficient.

Objective Lens Size Meaning

The second number out of the two refers to the size of your objective lens within your binoculars.

A wider objective lens will bring more light into your image which is great for using your binoculars when viewing stars or during low-light situations, so, for example, 10x50 pair of bincoulars will be better than a 10x35 in this case.

The bigger the number of this objective lens however normally means the heavier your binoculars will be, so if you want your binoculars to be portable you should ensure your objective lens is not too wide.

The FOV Number Explained

On your binoculars, you will likely come across a number referring to feet per 1000 yards or metres per 1000 metres.

A higher number will mean you have a more horizontal width of view when looking through your binoculars, a higher magnification, however, will limit this number.

On average 300-375 seems to be typically the best for most professional binocular users when out on the field.

What Is The Angle Of View?

The angle of view on your binoculars is the same as the field of view on your model and tends to be expressed in degrees.

For the best binoculars, this number always tends to be over or around 6 degrees and is usually expressed as a decimal which can be timed by the magnification of your binoculars to reach a total angle of view.

Close Focus Number Explained

A close focus number is important if you want to be viewing objects up close in detail which many binoculars are not that great at doing.

For subjects such as birds, this can be quite important with binoculars allowing you to see subjects up to 6 feet away from to 15 feet depending on the model you buy.

Exit Pupil Number Meaning

The exit pupil number on your binoculars will be measured in mm and refers to the two dots located in either eyepiece of your binoculars.

This number is a result of the division between the objective lens size and magnification. Generally, the bigger the exit pupil on your model the better as this will improve your image.

What Is Eye Relief?

Eye relief refers to the distance you can be from your binoculars and still see a full range of view which is important for users who wear glasses.

This number will typically be in mm again and should be from 10-15mm for people who wear glasses.

Which Are The Best Numbers To Look Out For On Binoculars?

The numbers you should prioritise on your binoculars can differ according to the use of your model.

For example, if you want to do hobbies such as stargazing, a higher magnification number will be much more essential for you rather than a wider objective lens.

We have listed out the best numbers to look for in your binoculars below according to different uses.

Birdwatching

For birding, your magnification number should range from 8x-10x depending on your budget and style of birding. The objective lens diameter number of your model should be between 30mm-42mm.

In terms of field of view, your model should range in between 8-6 degrees depending on the magnification chosen and have an exit pupil of at least 5mm.

Eye relief for birdwatching binoculars comes down to whether or not you wear glasses, so the higher the number the better in this case and a close focus of fewer than 2m can be great for up-close bird watching.

Stargazing

For stargazing binoculars, your are looking for a magnification number of in-between 10x-15x, most people assume you need a higher magnification of around 20x for stargazing but this is not the case as it will limit your field of view which is important constellations and connections.

The objective lens number of your stargazing binoculars should be quite high of around 50mm and above as you want your binoculars to be able to work effectively in low light to see the stars.

For the field of view, your stargazing binoculars should come with a range of over 300ft and have an exit pupil of at least 5mm.

Sporting

Sporting events will require your model to have a magnification number of around 8x-10x with a wide field of view between 6-8 degrees.

The objective lens can be smaller in these binoculars as your looking to save on weight due to holding these binoculars for long periods when spectating.

Hunting

As hunting requires you to be tracking moving objects, you should prioritise a wider field of view in your model from 6-8 degrees.

Magnification should be sufficient at a number of 8x and close focus is not as important on these models, as most subjects when hunting is far away.

An exit pupil of around 4mm is enough for hunting purposes during daylight.

Concerts

The best binocular numbers for concert viewing can be under 5x magnification and be very compact, as it is likely what you are spectating will not be that far away, and you will be holding the bincoulars for long periods.

Make sure the numbers for these binoculars range between 6-7 degrees for a wide field of view.

Frequently Asked Questions About Binocular Numbers

When should I buy high magnification binoculars?

Higher magnification binoculars are best suited to astronomical purposes or when viewing subjects from very far away.

8x, 10x, and 12x are sufficient for general use and zooming here and there.

Where are large objective lenses suited best?

You will need large objective lenses in low light scenarios such as night hunting or star gazing, the wider your lens, the better the low-light image will be produced at the other end.

What's the best eye relief for someone who wears glasses?

For someone who wears glasses, an eye relief of at least 15mm should make your experience more comfortable when using binoculars.

You can also adjust the dioptre on your binocular to match your vision if you would prefer to use your binoculars without glasses.

How do I calculate the exit pupil number on binoculars?

You can find the exit pupil number of your binoculars by dividing the objective lens diameter by the magnification your model which will produce a decimal or single number, for example, 10x50 binoculars have an exit pupil of 5mm.

A higher exit pupil means a brighter image will be provided by your binoculars.

What is a powerful binocular?

A powerful binocular refers to a type of binocular that has a magnification of above 20x and more.

These models often have to be used with tripods and are great from moon viewing and have an eye relief of 20mm and above making them excellent to use for people who wear glasses.