Binoculars may be daunting, especially with the deluge of information that producers and reviewers offer. But if you want to make a purchase, it’s crucial to comprehend the various figures of binoculars. For instance, what does 20 x 50 binoculars mean? Examining the number x number formula in more detail will help us better understand what it tells us about the optics it depicts.

What does 20 x 50 binoculars mean
What does 20 x 50 binoculars mean? Source: Bushnell

What does 20 x 50 binoculars mean and how far can you see with 20×50 binoculars?

A pair of 20×50 binoculars will magnify 20 times and have objective lenses that are 50mm in diameter. An exit pupil of 2.5 mm will be provided by these binoculars (objective lens divided by magnification). This size exit pupil offers adequate daylight power and good cloudy or late-afternoon visibility.

The 20x50mm have a 45-foot close focusing distance, anything closer than 45 feet will look blurry.

Understanding Binocular Numbers and Terminology

Magnification and Lens Size

Usually, binoculars will be described as being 10×50 or 20×50, but what do those numbers actually mean?

The first digit indicates magnification. When viewed via our 10×50 pair, objects will appear ten times closer than they would to the unaided eye, and 20x50s will magnify objects twice as much. Our buying guidance page lists the best magnification ranges based on the various applications.

A set that is marketed as 10-20×50 has variable zoom and can be magnified by any factor between 10 and 20. Near your right thumb, there is a little lever that controls the magnification on these.

Source: ACCU Scope

Exit Pupil Size 

This is a crucial element in figuring out how well binoculars perform in low light. The diameter of the light beams that actually exit the eyepieces is known as the exit pupil size.

It is calculated by multiplying the objective lens’s diameter by the magnification. Therefore, the exit pupil size of 20×50 binoculars would be 50/20, or 2.5mm.

The objective lens’s diameter in mm is indicated by the second number. The huge lenses at the far end of the binoculars are the objectives. Large objectives collect more light; doubling the lens’s diameter increases light collection by a factor of four. 

This is crucial in low-light situations, such as during astronomy or watching birds at dusk. However, despite their exceptional performance, 100mm objectives make for a huge and heavy set of binoculars that are difficult to manage. As with everything, we aim to reach an amicable solution that respects how you use your binoculars.

Your pupil will shrink to a size of 2-4 mm in sunshine. However, they will open to 7mm at night. Your age has some bearing on this. Binoculars with a 4mm exit pupil size appear as bright as those with a 6mm exit pupil size in daylight because if the light beam is broader than your pupil it can’t all get through. The binoculars with a 4mm exit pupil appear dimmer than those with a 6mm exit pupil because in low light conditions your pupils may open to 6mm.

Our eyes’ ability to see smaller objects declines as we age. For example, a 50-year-old observer might only have 5mm-wide pupils. Large exit pupils are of little benefit to these individuals.

What are the 20×50 binoculars useful for?

 With a pair of 20×50 binoculars, you may observe far-off objects like ships at sea, planes flying overhead, stadium sporting events, mountainous landscapes, or even the moon and planets.

Using 20×50 binoculars to observe nature or birds

Two things need to be taken into account when choosing a pair of 20x50mm binoculars for birdwatching, wildlife viewing, or other outdoor activities: portability and handheld observation.

The 20×50 binoculars would not be the preferred option for any birdwatcher or nature viewer due to the aforementioned concerns.

In actuality, what you’ll need in this situation is compact, waterproof binoculars with a maximum magnification of 10x handheld observation.

This does not imply that you cannot use these binoculars to view wildlife, birds, or other natural phenomena. If you don’t mind carrying around extra weight and using a tripod, you can accomplish it quite well and enjoy yourself in this situation.

But do you recall that we previously discussed this pair of binoculars’ 2.5mm exit pupil? So, have that in mind. You won’t have a fantastic experience if you are doing observations at dawn, dusk, in a forest, or in any other low-light situation because your image will be blurry.

Using 20×50 binoculars in astronomy

Because the exit pupil of a pair of 20×50 binoculars is just 2.5 mm, they are not a good option for astronomy, at least not for deep-sky viewing.

With this magnification, you can still see the beauty of the moon, its shadowy craters, Jupiter’s four major moons, and even Saturn’s ringed moons.

When stargazing or viewing deep-sky objects, the zoom or magnification ratio only plays a minor effect compared to the amount of light your binoculars or telescope can gather. These far-off objects in the deep sky are also exceedingly dim.

Using 20×50 binoculars for sport stadium or music concert

A 20×50 pair of binoculars can be used for stadiums like football, but it would be difficult due to the impossibility of using a tripod for stability. Thus, it is best to use a 20×50 binoculars as long as it has image stabilization.

You need a pair of binoculars to follow players directly on the field if your seat is toward the rear of the stadium. Due to its size, weight, portability, and flexibility to be used without a tripod, a 10x42mm might be a preferable option.

What does 20 x 50 binoculars mean? 20×50 Binoculars for watching concert or sport game. Source: Canon


Are 20×50 binoculars any good?

They are incredibly sharp, and despite the magnification, they are surprisingly simple to hold steady. They weigh a little bit more than, for example, a set of small, lightweight binoculars, but they are still wonderful.

What substitute for a 20×50 pair of binoculars can you suggest?

The exit pupil and poor performance in low light conditions would be the downsides of a 20x50mm. In order to improve your experience with astronomical viewing in low light, you should choose a pair of 20x80mm from Skymaster.

Should I prioritize getting 20x magnification binoculars or anything else?

For many situations where you might be able to utilize binoculars, 20x magnification is not a bad choice. However, if you wish to undertake the handheld observation and carry a tiny, portable pair of binoculars, a 10x would be a better choice. Also, 25x+ binoculars are used for moon and planetary observations for a better experience.

In conclusion

Just consider what you need it for and where you may use it if you are still debating whether to get 20×50 binoculars. We would advise choosing something like the 10x42mm from Nikon if you need something compact and portable. 

However, if you want to start doing astronomical observations, a 20×80 or 25×100 would be a fantastic choice. In any case, a 20×50 pair of binoculars can create a special experience for observers.