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Monocular vs Binoculars: Which Should You Use?

Last Updated on October 24, 2020

Monoculars vs. Binoculars

The main difference between a monocular and a pair of binoculars is obvious. Binoculars have two viewing tubes, while a monocular has one. But are two tubes always better than one?

Well, the short answer is no. There are many occasions where you’d probably prefer using a monocular to a set of binoculars. However, in the optics world, monoculars tend to get overlooked, and that’s very unfortunate. A good monocular can easily perform just as well as some of the best binoculars along with some extra added perks.

In this article, you will learn the key differences between a monocular and binoculars, what are the pros and cons of each, and in what situations you’d want to use either of them.

Monocular Overview

A monocular is essentially just a set of binoculars cut in half. They’re similar to telescopes in that they only have one viewing tube, however, the magnifications are not nearly as strong. Not just that, but telescopes use a different set of optics to process light.

Monocular diagramThis grey area of not-quite binoculars, not-quite a telescope, lands them in an overlooked shadow of the optics world. However, it’s this exact ambiguity that makes them perfect for many different tasks.

Applications

Let’s look at some of the features that make monoculars a solid choice for many optic users and more than just a “one-eyed binocular”.

Monoculars are smaller and less clunky than traditional binoculars, so they can be a great choice for a carry-along magnification optic. There’s also less of a chance of knocking it around on something and causing damage.

Most monoculars are very lightweight as well and have straps that allow you to more comfortably wear them around your neck. Although many binoculars have this feature, they are often much heavier, and over time, will weigh you down.

how to choose a monocular you’ll love

Lens & Prism

The lens and viewing mechanism of a monocular often utilize the Porro prism design. This design, originally used in binoculars and developed by Ignatio Porro in 1854, works on the principle of a curved lens acting with a prism.

The lens is designed to capture the light from farther distances and amplify it, while the prism takes the image and inverts it. This is particularly important because when the light is amplified the image that is produced is upside down thanks to the lens shape.

how to choose a monocular you’ll love

These two mechanisms are generally the most expensive part of the monocular to produce. This is why you’ll almost always find that a monocular is cheaper than a set of binos.

What's the Difference Between BaK-4 and BK-7 Prisms?

Most intermediate to high-end optics use BaK-4 or BK-7 glass Porro or Roof prisms. Both types were created by German optical glass manufacturer, Schott AG. BaK-4 is a glass designation that represents BaritleichKron (German for “Barium Crown”). It has a higher refractive index than BK-7 glass, meaning more light from the periphery of the field of view gets through the prisms and reaches the eyepieces. This brightens the edge of the field while leaving the middle intact.

BK-7 is generally considered “cheaper” and less desirable than BaK-4, but it’s actually better in some applications such as astrophotography.

Magnification

When it comes to magnification, monocular and binos are on a level playing field. After all, a monocular is just one half of a set of binoculars. But there are some effects of looking at magnified objects with just a singular view tube.

Monocular sizes

Using a monocular for extended viewing purposes places a lot more strain on your eyes than a set of binos would. With one eye’s vision magnified and the other not, your eyes will quickly grow tired when looking through a monocular.

That’s why a monocular is best suited for quick glimpses and not full-on observation.

Field of View

There’s no denying the edge that binoculars have when it comes to the field of view. The twin viewing tubes allow for a wider range of vision. But that gives the monocular a very particular edge in night vision situations.

Solomark night vision monocular

By only using one eye for night vision operations, you won’t ruin your natural night sight completely. And your eye that’s using the night vision monocular will be able to readjust to the dark much faster than if night vision binos are used.

Monoculars have roughly the same field of view as telescopes. Whereas binoculars give you a wide angle viewing experience, monoculars have what’s known as “true field of view”. Because monoculars are used for precision spotting of targets, their field of view is less of a concern. In fact, the less field of view, the better.

Telescope field of view

Pros & Cons of Using a Monocular

Pros
  • Smaller and more compact
  • Easier to adjust on-the-fly
  • Much better for night vision purposes
Cons
  • Smaller field of view
  • Using one eye isn’t a natural feeling when observing long term
  • More eye fatigue

Binoculars Overview

If you’re looking for a real general-purpose optic, a good set of binoculars is probably your best bet. They’re handy in just about every situation you’d need an optic.

Binoculars diagram

Let’s compare how a set of quality binoculars stands up to the same criteria as the monocular above.

Applications

You can use binoculars for just about anything you need optic enhancement for. And they’re comfortable to use even for extended periods of time. Use binoculars with ease at sporting events, tracking deer, or just exploring the urban jungle.

Father and son hunting with binoculars

Image credit: LightField Studios, Shutterstock

However, while they may be comfortable on your eyes, binoculars can get heavy. And although most binos come with a strap or sling that allows you to wear them around your neck or off-shoulder, they tend to weigh you down over time. They also take a bit longer to focus when compared to a monocular because you’re having to reconcile two sets of optics instead of just one.

Lenses & Prisms

Binoculars work off three systems: Porro, Galilean, or Roof prisms. As a matter of fact, Galilean monoculars were developed first, and the Porro and Roof prism styles evolved into modern binoculars.

3 types of binoculars

However, the monocular has a slight advantage here because there’s only one set of prism and lens instead of two. That’s because this is the most expensive part of the entire optic, and with binoculars, you have to pay for both.

Magnification

Binoculars and monoculars have very similar magnification specs. They generally come in the same levels of amplification. They amplify enough to give you a clearer image at a distance, but don’t quite boost it enough for extreme distances or in-depth astronomy — you’ll need a telescope for that.

Binocular objective lens size diagram

However, looking at magnified images for extended periods of time causes eye fatigue. And this is where the binoculars truly shine. Since you’re using two eyes to look through a set of binos, one eye isn’t doing all the work like with a monocular. This allows you to utilize binoculars for a longer period of time with less eye fatigue.

Field of View

Even the worst set of binoculars will have a bigger field of view than the best monocular. And that’s because you’re using both eyes! The twin viewing tubes allow for a much wider range of vision. This makes binocular ideal for scouting, scanning, and watching active events.

Binocular field of view

However, they’re not so ideal in night vision situations. Using both eyes with night vision tech will completely kill your body’s natural adjustment to low-light-level situations. This is why military personnel and special forces prefer night vision monoculars. They make it easier for your eyes to readjust to their natural night vision.

Pros & Cons of Binoculars

Pros
  • Much greater field of view
  • More natural feeling of use than monocular
  • Minimizes eye fatigue
Cons
  • Heavier
  • Pricier
  • Bulkier

Price

When it comes to optics, you generally get what you pay for. Fortunately, though, you have options, especially when deciding between getting a monocular or a set of binos. A top-notch monocular will always cost less than binos of the same (or even lesser quality).

And that’s simply because with binoculars you’re paying for double the protective shell and double for the lenses and optic components. So as far as price is concerned, monoculars are the clear-cut winner.

But that doesn’t mean that it isn’t worth picking up a quality set of binoculars. If you’re looking for something with a much greater field of vision, you’ll need the binoculars regardless.

Which Should You Use?

When comparing when to use a monocular over a set of binos, you need to look at the big picture — literally. Are you going to need a bigger field of vision? If you can’t answer that with a definitive yes, there’s a good chance that a monocular will work out just fine for you.

When to Use a MonocularWhen to Use Binoculars
Bird watchingStationary hunting
Spotting for long-distance riflesScouting and tracking
GolfSporting events
HikingEquestrian activities
Night visionMarine sightseeing

Which is Right for You?

So, which is right for you? Again, that all depends on exactly what you’re doing. We’d actually recommend owning both. Carrying around a monocular is much easier and less bulky. And it won’t set you back as much as binos if it gets broken.

However, you should always have a pair of binoculars on hand. While they may be bulkier at first, the long-term comfort and minimal eye fatigue they produce is an absolute blessing. Plus, they’re among the most versatile optic available and will work in just about every scenario.

About the Author Robert Sparks

Robert’s obsession with all things optical started early in life, when his optician father would bring home prototypes for Robert to play with. Nowadays, Robert is dedicated to helping others find the right optics for their needs. His hobbies include astronomy, astrophysics, and model building. Originally from Newark, NJ, he resides in Santa Fe, New Mexico, where the nighttime skies are filled with glittering stars.