How To Compare Binoculars (picking the right pair for you) 

How To Compare Binoculars (picking the right pair for you) 

Whether you’re looking to buy your first pair of binoculars or replacing your current pair with an upgrade, choosing binoculars can be confusing. With so many different brands and models to choose from, it can be difficult to know where to start.

Which is where this article will be helpful, here at Binocular Base we know binoculars and we can clarify the confusion and help you to see a clearer image of exactly which type of binoculars you need. Keep reading to find out more.

Everyone Is Different & Has Different Requirements

When you’re looking for binoculars you need to understand that we all have different requirements and what’s absolutely perfect for one person could be completely wrong for someone else. There really is no one-size-fits-all when it comes to optical equipment.

You need to consider the features that are available in modern binoculars and choose the pair which display all or most of the features that you require. 

Binocular Features

Roof Prism and Porro Prism Binoculars

Now let’s get into the different features available in binoculars and give a brief description of each to give you some understanding of exactly what you’re looking for;

Binocular Types: Porro Prism Or Roof Prism?

Let’s get started by looking at the two main types of binoculars, before the 1960s you wouldn’t have had this choice because there was only one type of binoculars, but more on that below.

Porro Prism Binoculars

These are those traditional types of binoculars with the eye pieces closer together than the objective lenses. Up until the 1960s all binoculars were made this way. However, they have been almost completely superseded nowadays because they are bulkier, heavier and less able to withstand any rough treatment.

Holding a pair of Porro prism binoculars for extended periods of time can feel uncomfortable especially when compared with the other type of binoculars. Having said that, some people prefer Porro prism binoculars because of their classic look and often lower price tag.

Roof Prism Binoculars

These are the narrower, more stylish looking binoculars which have straight barrels. This design makes for a more compact, easier to handle and lightweight pair of binoculars which appeal to modern users.

Roof prism binoculars tend to be more robust, able to withstand the rigours of British weather and have nitrogen purged, sealed metal or polycarbonate barrels typically covered in a rubber protective coating to reduce any likely damage through mishandling.

Pretty much all top of the range binoculars from all of the leading manufacturers feature a roof prism design.

Magnification

All binoculars will have a set of numbers printed on them somewhere. They will be separated by an “X” and the numbers before the “X” indicate the amount of magnification you will see when looking through the lenses.

For instance a pair of binoculars which has “10×42” stamped on them will have a 10 times magnification (we’ll get to the other number in a minute). If you’ve never owned a pair of binoculars before, you might be thinking that the higher the magnification, the better.

And whilst that may be true in some instances, after all, the whole point of binoculars is to see far off objects, in many cases it’s not that simple. There are other factors that come into play, this is because when you increase the magnification, you also decrease the brightness of the image, the depth of focus and the field of view.

Plus, the higher the magnification the more likely the image is to appear blurred due to your natural hand shakiness which is exaggerated by the magnification level. This is particularly prevalent in older people, which means for many people lower magnification works better.

However, most people agree that a magnification level of between 7x and 10x is great for many activities. If you decide to go higher than 10x you might want to consider using a tripod to support the optics to eliminate hand shakiness, but that limits your options to being static when using your binoculars.

Objective Lens Size (optical brightness)

The other number that’s stamped on the binoculars, the one on the other side of the “X” , is the size of the diameter of the objective lens in millimetres. The objective lens is the lens furthest away from your eyes as you look through the binoculars.

It’s called the objective lens because it’s closer to the object that you’re viewing. The larger the objective lens, the more light that is allowed to enter the binoculars which in turn, improves the brightness of the image you can see.

Having binoculars with a larger objective lens diameter is best for those people that tend to use their binoculars at dawn or dusk. Or those that are looking into dense, dark woodland for example.

The larger the objective lens, the heavier and more bulky the binoculars tend to be which means there is some compromise needed here as well. For practical purposes the most useful size objective lenses tend to be anywhere between 30mm to 50mm but remember the weight to size ratio.

It will be you that has to carry the binoculars around and hold them up to your eyes for extended periods.

Binoculars Size

Binocular Sizes

Binoculars tend to come in three sizes which are;

  1. Compact -Binoculars with an objective lens lower than 30 mm
  2. Mid Size – Binoculars with an objective lens size of between 30-40 mm
  3. Full Size – Binoculars with an objective lens size 42 mm or more

Obviously as the size of the objective lens increases, so does the size and weight of the binoculars. This means that different occasions could dictate different sized binoculars. 

For instance, if you’re trekking through a large area and carrying everything you need on your back, you’re going to need a small, lightweight pair of binoculars that can easily fit in a pocket or your backpack.

However, if you’re sitting in front of a large picture window looking out to sea, a larger pair will probably suit you better. When it comes to the size of the pair of binoculars you choose, your own personal strength and ability has to be factored into the decision making.

The Field Of View

As we mentioned earlier, the higher the magnification a pair of binoculars has will affect the field of view. Depending on the activity you’re using the binoculars for, the field of view plays an important part.

A wider field of view makes it easier to scan large, wide areas making it easier to follow fast moving birds or animals across open fields. The field of view will be measured either as an angle (a typical range for binoculars is 6o to 8o) or as a linear measurement of the number of metres visible across the field at a distance of 1000 metres.

In some cases the linear measurement might still be in yards over 1000 yards. The field of view will usually be displayed on the binoculars somewhere.

Eye Cups

Most modern binoculars have adjustable eye cups to make them more comfortable to use. Many of the lower priced options have rubber eye cups that can be folded up or down.

More expensive models can have plastic or metal, rubber coated eye cups that can be twisted up and down as needed. The eye cups help you to hold the binoculars at precisely the right distance from your eyes to see the full field of view with comfort whilst preventing excess external light from spoiling the view.

If you wear eyeglasses, you can twist these eye cups fully down to bring your eyes closer to the eyepieces whilst still wearing your glasses.

Eye Relief

The eye relief in binoculars refers to the furthest distance a user can place their eyes behind the eyepiece and still see the full field of view. Obviously the eye relief is more important to eyeglass wearers because the glasses have to fit between the user’s eyes and the eyepiece of the binoculars.

If you wear glasses, you’ll need to look for binoculars that specify long eye relief. Long eye relief is typically a measurement of 16mm or more. However, depending on the type and thickness of your glasses, you may need a pair of binoculars with an eye relief of 18mm or more to get to see the full field of view.

The Optical Qualities Of The Lenses

child using binoculars

Obviously the optics of the binoculars is an important factor when considering which pair to buy. There are a number of optical factors mentioned in many of the more popular and well respected binoculars which include;

ED Or HD Glass

Extra-low dispersion (ED) or high density (HD) elements in the glass of the objective lenses are designed to reduce chromatic aberration. This is where the image has a bright colour fringing around it when you’re looking through the binoculars.

Objects viewed through binoculars with ED or HD glass have a crisper, sharper, more defined quality and the colours tend to be more true across the whole spectrum. This means the image looks more natural through ED or HD glass making them ideal for any number of applications including birdwatching and nature watching.

Lens & Prism Coatings

The quality of the optical coatings makes the real difference between OK binoculars and outstanding Binoculars. These coatings are typically high performance, anti-reflective and high transmission coatings and are used to improve light transmission as well as reducing internal reflection.

Pretty much every pair of binoculars on today’s market use some form of coating to improve their optical quality. However, the coating varies greatly from manufacturer to manufacturer and the overall price of the binoculars can dictate the level of coating. As a general guide;

  • Coated
    This means that some of the surfaces have been coated with a special optical coating.
  • Fully Coated
    This means that all glass surfaces have been coated
  • Multi-Coated
    This means that some of the glass surfaces have been coated with multiple layers
  • Fully Multi-Coated
    This means that all of the glass surfaces have been coated with multiple layers of special optical coatings

If you want to get the best from your new binoculars, you need to buy a pair that are fully multi-coated.

Anti-Reflection High Transmission Coatings

The higher end, top of the range binoculars have multiple layers of anti-reflection high transmission coatings applied to their optical glass. This reduces internal reflection and creates a sharper, brighter image. 

However, this is a difficult and expensive process which does increase the cost of the binoculars considerably.

Phase Corrected Roof Prisms

Roof prisms work by splitting the light that passes through them and recombining it as it continues through them. Unless the prisms are phase corrected, these light paths can become out of phase which results in less contrast and detail once the image has been recombined.

A decent pair of roof prism binoculars will have a special phase correction coating applied to prevent this from being a problem.

Roof Prism Mirror Coatings

The design of roof prisms also needs a special reflective mirror coating on one of the prism surfaces to reflect light through the prism and onto the eyepiece. The higher the light transmission of this coating, the brighter the image will appear in low light conditions.

There are three main mirror coating types which are used to coat the roof prisms which are;

  1. Aluminium Mirror Coating
    This type of coating typically results in a light transmission of 87 to 93%
  2. Silver Mirror Coating
    This type of coating typically results in a light transmission of 95 to 98%
  3. Dielectric Mirror Coating
    This is the most expensive coating which is typically found on high end, high spec binoculars. It results in more than 99% light transmission

Protective Coatings

Many of the higher spec binoculars are coated with a high tech coating to protect the more delicate coatings already applied to the external surfaces of the lenses. These robust coatings are designed to resist scratches and abrasions as well as reduce the need for cleaning the lenses as they also repel dirt and water.

Plus when the lenses do need cleaning, it takes less time due to the coating. Many of the mid priced range of binoculars are starting to incorporate these protective coatings now. 

Which means if you can afford to spend slightly more than you originally anticipated, you could get a pretty high quality set of optics.

Handling & Balance

Binoculars

Larger binoculars tend to be more difficult to handle than smaller more compact models. However, even some larger models are ergonomically designed for ease of use.

Factors that affect the weight of the binoculars include;

  • The size of the objective lens
  • The material used in the construction
  • The length of the binoculars

Having said that, the size and shape of the binoculars that you choose is a personal matter. What suits one person might not suit someone else.

Fog/Waterproofing

In an ideal world, we’d only ever use our binoculars on clear, dry days. The reality however, is something different. Even if the day starts off bright and sunny, the rain clouds can roll in at any time.

This means you need to choose a pair of binoculars that have protection from the weather. We recommend buying binoculars that have been purged using an inert gas like nitrogen or argon.

This will remove air and any moisture which prevents the internal lenses from fogging up or condensing. This can be very useful when moving from the confines of a warm car and out into the cold or damp lakeside air.

Bridge Type

Many traditionally designed binoculars have a single bridge which hinges. However, many manufacturers are now incorporating twin bridge models into their ranges.

These twin bridged models can offer some more in the way of ergonomics and comfort especially if you’re holding them for extended periods.

Housing & Rubber Casing

One of the main factors that dictates the overall weight of the binoculars is the material used to make the housing. It is also the main form of protection for the delicate optical systems.

Which means the ideal binocular housing needs to be lightweight and very strong. In their search for lightweight and durable binocular housing, manufacturers have opted for three main materials, which are;

  1. Polycarbonate
    This material is strong yet lightweight and costs relatively less to produce compared to the other types of materials used for building binoculars. Polycarbonate housings tend to be found on many low to mid priced ranges of binoculars.
  2. Aluminium Alloy
    Aluminium is a light yet strong type of metal alloy and is often found in many mid to high priced binoculars.
  3. Magnesium Alloy
    This is the strongest and lightest of the three materials used in the construction of binoculars and is to be typically found in high end optics and premium models.

As well as a strongly constructed housing, pretty much all modern binoculars will also have some level of rubber protective coating applied to both barrels to help prevent accidental damage. This coating not only protects against bumps and scrapes, but also helps improve grip and ensure that holding the binoculars is comfortable as well.

Some even have moulded hand grips for even more comfort and improved handling.

Close Focus

Close focus is the information that lets you know how close to the object you can be and still see it as a sharp, clear image. This can be useful for birdwatchers and others who enjoy a close up look at nature.

Binoculars that have close focus as a feature tend to state something like “close focus 2 metres”. Which means that you can view clear images of objects from as little as 2 metres away.

The Price

In an ideal world, we’d all plump for the most expensive option recommended for the particular pastime we enjoy. However, the reality is we all have a budget. It’s worth remembering that the cheapest option isn’t necessarily going to offer the best in terms of value or quality.

Depending on the activity you intend to use them for, your binoculars will most likely be the most important piece of kit you will need to buy. If you intend to use them on a regular basis, the overall cost will work out less over time.

Buying a mid priced or even high spec pair of binoculars will be a better investment. This is because they will offer you better, more resolute images in a range of light conditions.

Plus they will have a more robust construction and be resistant to the weather and other elements like dust etc. Obviously you are the only one that knows how much money you can realistically afford to spend on a pair of binoculars.

But, the better quality they are, the more likely you are to use them regularly and the more enjoyment they will give you.

SEE ALSO: Which Brand Makes The Best Binoculars?

Frequently Asked Questions

What does 10×42 mean on binoculars?

10×42 on binoculars means they have a magnification of 10 times and an objective lens of 42mm. This is a popular size amongst many binocular users including birdwatchers and those watching sporting events.

Is it better to buy binoculars with a high magnification level?

Whether you buy binoculars with a higher magnification level or not depends on the activity you are using them for. The higher the level of magnification means a decreased field of view , decreased field of depth and a decreased level of image brightness.

Is it good to get a large pair of binoculars?

Larger binoculars can be good but it’s worth remembering that larger binoculars will weigh more making them more difficult to carry and to use. Generally, any binoculars with an objective lens of more than 45 mm will be heavier, more bulky and harder to hold for long periods.

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