Binoculars Buying Guide

Binoculars Buying Guide

I want to give you some quizzes!

Consider Nikon Prostaff 3s model’s two products namely 8×42 and 10×42. The first model has 8 power magnification (8 times magnification) where the second model has 10 power magnification (10 times magnification). Which are the best binoculars?


The price difference between the two models are very negligible. If you compare the usability of these two models you’ll find the 8×42 model beats the 10×42 model in every way (other than the magnification)! This is because higher magnification doesn’t ensure better performance! 

Okay that was an easily question. Now look at the specs of the two binoculars below and guess the most expensive model!

Swarovski Vs Barska Price Comparison


So what’s you take?

When you consider only the specs, you are likely to think Barska 8x42mm WP would cost more than Swarovski EL SwaroVision 8×32. Although they have very similar specs, the Barska 8x42mm WP has a better Field of View and minimum focus distance.


Interestingly, Barska 8x42mm WP costs about $350 whereas Swarovski EL SwaroVision 8×32 goes for over $2,200. Strange! Isn’t it?


But, why is that so?


Well, the features and specifications of a binocular don’t necessarily determine the price.


So, what determines price?


Binocular manufacturers are working around the clock to provide us with a perfect image. Some of the common problems the users experience are the loss of brightness and color, crispness, depth of field issues, fringing, and chromatic aberration. Many of these issues are compounded in challenging light environments such as in the shady woods or during sunrise/sunset.


Many of these issues can be solved or reduced, but that someone has to incur the cost.


There is no doubt that the binocular industry is indeed competitive, and there are many great companies and models on the market. Birding or hunting binoculars can cost anywhere between $100 and $3,000. Since the industry is very competitive, you get what you pay for.


Rule of thumb: the more money you are willing to spend, the better the performance you can expect!

However, like all rules of thumb, this ‘price rule’ isn’t always precise!

I have tested both Nikon Monarch 7 8×42 and Zeiss Terra ED 8×42. Nikon Monarch 7 8×42 features slightly better field of view and close focus distance whereas Zeiss Terra ED 8×42 features slightly better eye relief.

However in practice I didn’t notice any difference with field of view and eye relief between these two models. Moreover, Zeiss Terra ED 8×42 feels slightly more premium at hand than Nikon Monarch 7 8×42.

Zeiss Terra ED Vs Nikon Monarch 7

But Nikon Monarch 7 8×42 costs $80 extra ($480) than Zeiss Terra ED 8×42 ($400). So, here rules of thumb of ‘price rule’ is not precise at all.

***Attention: Most companies don’t reveal all the information customers need to know. These are not revealed so as not to lose a competitive advantage. For instance, Zeiss has been in business for a LONG time. They have perfected their engineering and coatings over many years and are not very willing to share their best practices with other companies!***

Deciding which binoculars to choose could be quite a daunting task. However, this binoculars buying guide should help you find the right pair of binoculars.

1. Decide the prism of choice

     a. Roof Prism vs. Porro Prism

Roof prisms have become quite popular in recent times. Thanks to their DCF designs the binoculars have become so common these days.

DCF stands for ‘Dach Centre Focussing’. ‘Dach’ is a German word for ‘roof’

They now outnumber Porro prisms in sales and demand. There are some ideal reasons for this. However, the main reason is their compact and elegant design – but they come with higher cost.

Surprisingly, porro prism models perform better than roof prism model when they have similar specs and features. They are the simpler models with on the low cost which will allow the manufacturer to spend less and still get the best images.

In roof prism binoculars, the light enters through and passes out of roof prism in a single/ same plane; which is technical to build and requires high-end technology. As a matter of fact, phase shift – which occurs in a roof prism, requires phase correction coating to rectify. These coatings need specialized skills, expertise, and also equipment, to correct. And all these cost more money.

That’s why phase correction coating is usually omitted from the cheaper roof prism binocular models. Those models produce image of slightly less contrast and lower resolution. On the contrary, porro prism binoculars don’t need phase correction coatings as no phase shift occurs in them.

     b. Bak-4 Prism Vs BK-7 Prism

Bak4 aka barium crown glass prisms are usually used in high quaity binoculars because of their higher refractive index than BK7 prisms. Higher refractive index helps collect more light from the periphery of the field of view (FoV) to the eyepiece lens. This produces an image with brighter edge that the BK7 prisms can’t produce very well. The difference is more noticeable in low magnification binoculars that have wide field of view. However, BK7 prisms can be better choice in some models especially those used in binoviewers.

Bak4 Vs BK7 Prism

Image: Bak4 Vs BK7 Prism


You can easily determine if your binoculars are made from Bak4 or BK7 prisms without reading the model number. Point your binoculars towards the open sky or any light source (but not the sun). If you see a bright and perfectly circular light in the eyepiece end, then the binoculars are made from BaK4 prisms. BK7 prisms will give a diamond shape light source with gray segments around it.

Note: The “BAK4” prisms used in lower quality binoculars are not the same as premium Schott BaK4 prisms. Cheap binoculars ususally, but not always, lebel the prism type as BAK4 (notice the upper case letter ‘A’) while the premium binoculars label as BaK4 with lower case letter ‘a’. Cheap BAK4 prisms are made from phosphate crown glass rather than barium crown glass. These lower quality BAK4 prisms has a lower refractive index than Schott BaK4 and produces an image this is not as sharp as found with Schott BaK4 prisms.

2. Pay attention to the important optical features that affect quality

If you want quality binoculars there are a number of optical features you would want to check:

a. Anti-Reflection Lens Coatings

Anti-reflection coatings assist with light transmission and in turn help to give out a brighter image with an overly better contrast.

These coatings are made up of extra thin and highly transparent film layers. Each layer usually has a distinctive index of refraction that will alter the lens performance by providing different wavelengths of light at diverse incident angles.

Fully Multy-coated (FMC) Lens

When it comes to anti-reflection coatings, Fully Multi-Coated optics are the best options that you should look for. They perform better and will leave you with some of the top quality images. In FMC lenses all glass-to-air surfaces receive multiple layers of coatings. Binoculars that describes Coated, Fully Coated, or Multy coated lens, they don’t receive anti-reflection coatings on all air-to-glass surfaces and thus give weaker light transmission.

Note: Some cheap binocular manufacturers also market their binoculars describing Fully Multicoated Lens. Most of them are just advertizing hype. Their coatings are inferior in quality: unevenly applied and with wrong thickness. Those fully multicoated optics can’t even perform near to the well applied single coated lenses.

b. Extra Low Dispersion (ED) Glass

The ED glass has been on the rise in the recent years. Before, only high end binoculars would use the ED glasses. But what actually does an ED glass mean? Why do we optical experts use ED glass? And how does an ED glass help to improve the quality of your binoculars? Let’s dig in to determine what it is.

ED Glass

Rainbow effect or color fringes around the edges (left); Clear image with ED glass (right)



Before looking at an ED glass, let’s first understand what dispersion is in optics. When you pass light through a prism you will break the white light beam into its component colors.

The blue end of the resulting colors is usually bent the most while the red end is specifically bent the least. The act of breaking this light into its component colors is what we refer to as dispersion.

Dispersion in a Lens

Your binoculars lenses work by focusing the light ray that they capture on a single point behind the lenses. But just like the prism a small amounts of dispersions occurs as the light goes through the lenses as well.

This phenomenon is known as chromatic aberration and manifest in form of color fringes around the resulting images.

Reducing the Dispersion

In order to eliminate the color fringes, you need to reduce on the dispersion. This can be done by the use of Achromatic Doublet, Compound Lenses, and Apochromatic Lens (APO) which will allow your binocular to gather up all the different light wavelengths and focus them on a single point on the plane for a crystal clear image.

So what Is an Extra Low Dispersion Glass?

Also know as HD glass, is a type of glass that can accurately focus all light spectrum toward the focal point as hence reduces light dispersion. Reduced light dispersion enables the glass to give superior sharpness and color correction. That’s why every type of high caliber lens has the ED glass component included. These glasses are however quite expensive.  Learn more about Extra Low Dispersion (ED) Glass.

Apochromatic (APO) Lenses

So what are Apochromatic (APO) Lenses and what do they do? Here is what you should actually know.

To give out an upright image in a binocular, light has to pass through a lens. When it does so in a single lens there is usually the distance behind that lens at which every single wavelengths of the light beam will come into perfect focus. This distance varies for every ray of light.

Nonetheless it creates a dispersion of the “white light” along the main optical axis. This causes a chromatic and spherical aberrations that result into you seeing soft images and also color fringing along the main edges of a highly-contrasting object.

This is not good for any viewer and in order to minimize this effect of chromatic and spherical aberrations. Optical designers will usually number of lenses with different optical abilities and also focal lengths to create a single “multi-element lens” which is also referred to as a compound lens.

Apochromatic (APO) Lens

When this type of resultant lens is able to bring two light wavelengths into focus in a single plane and ideally reduce the aberrations the lens will be called an achromatic lens. However if three or say more visible light wavelengths can be brought into focus at the same plane behind the resultant lens then the lens is referred to as an Apochromat/ apochromatic lens (APO).

What an APO Lens Will Do

Most APO lenses have three elements that give them the ability to bring light rays of three or many different frequencies into a single or common focus. This provides them with better correctional capability for any chromatic aberration and spherical aberration than the more common an achromatic lens.

Apochromatic lenses are easy to correct for the spherical aberration at the two wavelengths unlike the common achromatic lens.

They Are the Pricey Option

For an APO lens to focus the three or more light wavelengths onto the exact same point behind the lens they need special glasses.

These glasses must have specific light dispersion properties. Because of this optical experts will use extra-expensive fluoro-crown glasses or the abnormal flint glasses to design them. That’s why they are often used on roof prisms and the BaK-4 Prism in binoculars.

In other special cases these lenses are also designed using transparent liquid that are set in the thin spaces between two glass elements to create the most unusual dispersive properties.

Note: Whether achromatic or apochromatic lens, these lenses will usually contain at least a single element that will use a low-dispersion glass.

Bottom Line: With an apochromatic lens you will get a high caliber binocular that can easily focus more light wavelengths and thus give your binocular a high-end quality image at the viewer.

c. Phase Correction Capacity

Phase Shift occurs when the light ray which enters into the prism undergoes a two split when reflected around because of the polarization angle phenomenon. This provides a somewhat out-of-phase light beams that must be corrected to get the best image. The ability of your binocular to correct this effect is what determines the best image.

Remember, porro prism binoculars don’r need this phase correction capacity; only roof prism binoculars require it.

3. Check out Water-Resistant (or whether-resistant) Vs Waterproofing Spec

While many binoculars that we have today are water-resistant or whether-resistant, a closer examination to a number of inexpensive models reveals that they aren’t entirely sealed. Meaning that; some moisture and dust might still find their way into the device.

While waterproof models are fully sealed in their optical barrels by replacing air with nitrogen and then again sealed with O-ring.

Nitrogen purged system totally prevent the moisture, fog, dirt, and dust particles from getting into the binoculars and blurring the lens. O-ring sealing ensures the watertight barrier between between the lenses.

The Biggest Mistakes Newbies Make While Buying Binoculars

It isn’t a new sight for me to see quite a number of people; making so many common mistakes when they finally decide on choosing a pair of binoculars to use for their personal optical needs. In fact over the years that I have been actively involved with optics and more specifically binoculars, no day has gone by without me having to get an email asking about “why is my binoculars this or that way.”

Now looking back at all these carefully, I have found out that many of the guys who go through these are actually new to binoculars or simply took so many things for granted when they were purchasing. Partially, I also noticed that the optics experts like us have also contributed a lot to this.

“How?” you may ask. Well, we haven’t sensitized people enough on the basics. We have thought that because we know the most fundamental basics, everybody else knows about them – but that’s not true.

In this post I will outline some of the most common mistakes that newbies make while choosing their binoculars and what they need to do to avoid them.

#1: Buying a Low-Cost Binoculars

Looking for a cheap or low-cost binocular is a big mistake. Unfortunately many of us do it! You will find out that going for a cheaper model will expose you to so many vulnerabilities.

Indeed spending so much on a binocular will also be unwise if you are just starting out. But the truth is because building a great optics device will cost more; the price of a better model will be relatively higher.

#2: Going for Too Powerful Magnification

A powerful magnification is good. In fact, it will easily get the object under view as closer as you may want it to be.

However, going for an all too powerful magnifying capacity isn’t what you really need. Well here is why you shouldn’t go for very high powers especially in low cost optics.

Low-Quality Images: Higher magnifying capacities require very thick glass on the lenses. Thick glass will allow very less light to go through. Less light will mean dim images. Dim images are actually low-quality images. This can be very bad on low caliber optics.

Thin Field of View: The more you zoom in your picture, the lesser quality you get – as pixels enlarge. This might make it really hard to even find the object that you are actually zooming in on.

Image Shake Stress: High powers will prevent you from keeping the image that you are viewing really still. To get a still image from high powers you’ll have to spend on digitally stabilizing binoculars.

Note: Less clarity on your image isn’t what you are actually looking for. So why end up with the same? The most recommended magnifications are 8X or 10X magnification powers for the moderate optics.

#3: Buying Cheap Zoom Binoculars

On rare occasions, I have found good variable magnification binoculars on the cheap. But those are very rare cases. However, for lower optics or if you are on a budget, you will be safer and better with fixed magnification binoculars.

But why not, when most of these spotting scopes allow you to adjust your magnification by simply zooming in and out?

Here is what you must know really, binoculars are basically two sets of telescopes that are connected on one frame. They have to be properly synchronized if you must have a clear image and indeed that’s why you need a diopter.

Without the diopter or the ability to use it, you will find it really difficult to achieve a clear image if you need variable magnification. The reason is simple. The zooming technology requires moving lens elements in every ‘telescope’ so that it can continuously maintain its synchronization when on the move.

So without a high-quality zoom, you are bound to end up with blurred images and a device that will leave you disappointed.

#4: Buying a Binocular with Built-In Digital Camera

Any binocular with a built-in camera will easily allow you to take photos and at the same time capture videos. So what if I told you it is the worst mistake you can ever do? Which of course it is?

I know you must be getting disappointed already. Well, the truth is, the zooming powers of the two gadgets unless properly synchronized (which is rarely possible with low-cost devices) will be a real problem.

Without this proper synchronization your shots might be blur and of low quality, and so will your videos.

Here is my advice: Simply get good binocular or scope and buy a separate adapter that enables a camera to be attached on your binocular.

#5: Don’t be seduced by inexpensive top-end specs

Inexpensive binoculars are built in a way that their cost of production is kept at the minimum levels. Sometimes they may offer you with all the top-end “specs” but in reality, they won’t work at all.

So if you ever see all the top-end features packed in a pair of cheap binoculars never be deceived.

If you are on budget I recommend buying a mid-size porro prism model. They are affordable and will give you super quality bright image with large field of view.

#6: Look at construction materials

Construction material is another consideration that determines longevity and comfort. High-quality materials make the binoculars long-lasting, and thus expensive.

For example, Magnesium housing is used in expensive models due to its lightweight and long-lasting properties, Alluminum housing is used in middle class binoculars, while resins and plastics are used in the inexpensive models.

Although polycarbonate resins and plastics are tough and resistant to knocks and bumps but they are heavy in weight.

So, if you are on budget, I think it wouldn’t be much sacrifice to bear some extra weight at the cost of super quality bright image.

#7 Eye-cups

Eye-cups are another important body part of binoculars for adjusting eye relief depths to accommodate individual’s comfort.




Good pairs of binoculars come with adjustable eye-cups that lock firmly in place, while on some cheaper models you will find they can be knocked out of position easily. Long eye-relief binoculars (16-20mm) usually have 3 to 5 twist-up eyecup positions and they are much expensive. Average eye-relief binoculars (14-15mm) usually have 2 positions and are comfortable for most, if not all, eyeglass wearer.

#8 Diopter adjustment mechanism

In addition to the center focus wheel, a good pair of binoculars should have a separate diopter mechanism in the right eyepiece.

Diopter adjustment

Diopter adjustment


This diopter knob allows you to make adjustment in focusing one eyepiece independently, to fix the differences in your eyes. Cheaper binoculars may not have this mechanism. Sometimes premium models often have central diopter adjustment ring (rather than right eyepiece diopter).

#9: Ploys and tricks

The manufacturers of cheap binoculars will often try and use a specific feature to sell the binoculars.

For example, they feature “ruby coatings on lenses” simply because it is popular among blockbuster movies.

These coatings designed to eliminate red effect from the spectrum won’t actually remove color aberrations in low quality optics. So when you try them out the image will look unnatural and so much washed out.

Again, some cheaper binoculars claim to have close focus distance of 3-4 feet which is actually not true. Such a focus can only be achieved by looking through one eye only.

On the contrary, premium or at least mid-range models will give you the best value for your money.

You will typically get what you pay for. Whether in design, image quality, specs, rugged design, and the removal of color aberrations, the expensive models should be on point.

What to Look for in a Pair of Binoculars

For quite some time now, many people who are looking for the best pair of binoculars have been met by high-end jargons that can easily hit you off balance and leave you with a poor device.

Well, it is understandable that optical experts must use such terms as these are technical gadgets. But when looking for your pair of binoculars, you don’t have to go through all this pain sticking process.

In this post, I have explained in the simplest way possible some of the things that you must look out for so that you get the best pair of binoculars for your use.

Magnification and Objective Lens Diameter

One of the most important features in a pair of binoculars is the magnification and objective lens diameter, which is typically included in any binocular model information that you will find today.

For example, in the CIWA 10X42 HD Binoculars the “10×42” is the magnification x objective lens diameter.

Binocular Magnification

More specifically, the 10X is the magnification power. Magnification usually appear as 8X, 10X, 12X or higher and is basically the degree to which the object you are observing can be enlarged. A 10X magnification binocular means that the object under view in such a binocular will appear 10 times closer to you than they will actually do when viewed with the naked eye.

In short something that’s 500 yards away will appear as if it were 50 yards away under a 10X magnification capacity.

Because of this, magnification is often one of the most vital things that any binocular buyer will actually look for in any pair of binoculars that they choose to buy.

In the example, while 10X is the magnification power, the (42) refers to the objective lens diameter normally denoted in millimeters and which in this case will be 42 millimeters.

Simple as it seems, don’t be deceived, the lens objective size is actually very important. The larger lenses collect more light as compared to the smaller lenses. What this means is that objects under larger lenses will appear brighter in the binoculars.

Additionally, the size of the objective lens also greatly affects the field of view that you will have; read next about the Field of View.

Field of View

Field of View (FoV) is also very important when looking for a pair of binoculars. It refers to the total amount of area you can see through your binoculars when in focus.

Both the magnification as well as the eyepiece lens will play a major role here. In general, the higher the magnification, the smaller the field of view, and vice versa.

Actual and Apparent Field of View

When looking at the field of view statistics the units of measurements that you have dealt with will only include degrees and feet.

Degrees come in two numbers. These numbers represent actual degrees on the actual field of view and also degrees in your apparent field of view.

Actual Field of View: This is the angle of your viewing window which comes at the actual point after your set of binocular lenses.

Apparent Field of View: The apparent field of view is calculated on actual field of view. Because of this it’s actually the actual field of view numbers that really matter.

For example: A 10X binoculars with an actual field of view of about 5 degrees has an apparent field of view of 50 degrees. Simply multiply the actual field of view and the magnification power of your pair of binoculars. The resulting figure is the apparent field of view.

Eye Relief

Eye relief and field of view are closely related. It is the distance that you can easily hold the binoculars away from your eyes and still get the full field of view.  For people who wear eyeglasses, this feature plays a key role. If you don’t wear glasses then you don’t need to even worry about it.

Eye relief of 14-20mm or more is desirable for a person with glasses to enjoy the same field of view as any other normal person.

Exit Pupil Diameter

In dim light the ability of eye to detect full contrast and fine details of a object is reduced. To compensate this low light situation the pupils of eye dilate to its maximum.

In good light situation the diameter of pupils tends to lower to calibrate the amount of light imaged on the retina. However, the response of pupil to various light situations depends on the age of a person that is shown in the table below:

[table id=9 /]

The exit pupil diameter of binoculars is actually the measurement of the light ray that will actually hit your eyes once it travels through the binoculars lens.

How To Determine the Exit Pupil

In order to determine exit pupil diameter of your binoculars; hold your device with its objective lenses pointing towards the main source of light.

Then focus your device so that you get the best eye relief for your binoculars. The diameter of the circle of light that comes from this setting (when on focus) is the exit pupil.

A simpler way of determining the exit pupil without having to raise the binocular is: divide the size of your objective lens by the magnification capacity of your binoculars. If you obtain a larger number you get much light. This means the images you view under this binocular will also be brighter.

Close Focus Distance

Close Focus Distance is also known as Near Focus Distance. It is the distance between your binoculars and the nearest object that you can clearly focus.

In a good set of binocular, this distance should be at least 10 feet. But this only applies to the general purpose binoculars.

However, for high magnification binoculars (more than 10x binoculars) such close distance, is usually not practical to expect.

Some cheaper models may claim to use 3-4 feet close focus distance which is not true actually. Yet, some premium models from steiner, vortex and pentax make surprisingly close distance binoculars.

Eye Strain

Eye strain manifests through blurred vision, fatigue, and pain in and around the eyes, headache, and sometimes double vision. This can only happen if your lenses are of poor quality or if the optical alignments aren’t properly calibrated while manufacturing. The alignment of optical components is called ‘collimation’.

Improper IPD (Inter-pupillary Distance) adjustment also causes the edges of the field under view to blacken. It is basically the main distance from one eye pupil to the next.


This one refers to the general build of the binoculars. It answers concerns about grip, airtight build, durability, and size among many others.

The trick to choosing the best ergonomic design is to get a binocular that feel comfortable on your hold.

There you have it; the best way to choose your high end binoculars.