Understanding Binoculars Field of View

April 23, 2019 0 Comments

binoculars field of view

 

When we choose binoculars one thing that we should always remember is the the binoculars field of view aspect.

Though if you are a complete beginner in optics it may not be so critical.

Standard binoculars come with a pretty standard field of view that allows you to comfortably look through binoculars.

Some binoculars have wider field of view and experienced users may want a pair of binoculars above average optics.

But they normally have a higher price tag. So, let’s look into this aspect so you can understand it better when choosing a pair of binoculars.

First of all, you must know that high power binoculars have smaller field of view.

Binoculars with magnification 4x have bigger field of view than binoculars with magnification 8x or 10x.

Binoculars with magnification 8x, 10x have bigger field of view than binoculars with magnification 16x or 20x.

Just an example, below you can see the screenshot of three different binoculars with magnifications 10x, 12x and 20x.

Also, keep in mind that what you see on the screenshot is different from what you see the you look through binoculars.

 

magnification-10x-12x-20x

 

This was made with a phone camera attached to binocular lens.

When you look through binoculars you look with your two eyes and see bigger field of view that what you see on the screenshot above.

From my experience I believe magnification 8x, 10x and 12x is the optimal for general use and does meet needs of most users even those advanced.

These binoculars have a relatively wide field of view and give you an excellent experience.

But some advanced users may need high power binoculars to be able to view distant objects.

At this point we must understand that high power binoculars have smaller field of view.

Because when binocular magnification increases the field of view becomes narrower.

Technologically it’s impossible to overcome this barrier.

But as I said in my other articles about magnification, if you decide to buy high power binoculars smaller field of view shouldn’t be an issue at all.

Because your main goal when it comes to high power binoculars is to get a specific viewing object closer to you.

Otherwise you should choose binoculars with magnification between 8x – 12x for general use purposes.

Some brand binoculars from such manufacturers as Nikon, Vortex, Celestron, Orion, Oberwerk produce high power binoculars with a field of view wider than what you find in cheaper models.

If field of view is critical for you then I suggest that you take a look at these binoculars.

 

How to understand field of view in binoculars

First of all, we need to understand that field of view of the binocular doesn’t depend on the size of objective lens.

Field of view depends on the ocular lens and construction of binoculars prism.

The bigger the size of the ocular lens and the better the construction of the prism in the binoculars the wider is the field of view in the binoculars.

The bigger the objective lens the brighter is the image produced by binoculars.

 

objective lens

 

To know the size of the ocular lens (exit pupil) in mm you should divide the size of objective lens by the magnification power of the binocular.

 

For example, let’s take a look at Levenhuk binocular 12×50 (12 is the magnification and 50 is the size of the objective lens).

 

  Levenhuk Karma PRO 12×50
Magnification power 12
Waterproof/fogproof binoculars
Bak4 roof prism optics
Fully multi coated lenses
Customer satisfaction: 70%
Price: $114.95

levenhuk 12x50

4,8 score

 

 

So, 50:12 = 4.1 which is the size of an exit pupil of the binocular. 4.1 is pretty good size of an exit pupil.

Whenever you buy binoculars exit pupil should be at least 3mm.

For example, if you chose binocular 8×42 it means 42:8 = 5.25 is the exit pupil.

 

angle of view formula

 

Such binoculars normally have field of view between 5.8 degrees and up to 7. The higher the magnification the smaller is the exit pupil and vice versa.

 

angle of view

 

Some manufacturers mention angle of view instead of field of view. For example, if angle of view is 4.7 then we multiply it by 52.5.

 

Now 4.7 x 52.5 = 246Ft/1000Yds

 

This means Levenhuk Karma Pro 12×50 has a pretty good angle of view. The price of this binocular is $124.95

 

Another binocular Vortex Optics Crossfire Roof Prism Binoculars, 12×50 are more expensive ($179) and it has wider field of view.

 

  Vortex Optics Crossfire Roof Prism Binoculars, 12×50
Wide field of view
Magnification power 12x
Fully multi-coated high quality optics
91% Customer satisfaction
Price: $179

Vortex Optics Crossfire Roof Prism Binoculars, 12x50

4,7 score

 

Field of View is 273 feet/1000 Yds and the angle of view is 5.2. Though it has the same exit pupil size as Levenhuk Karma Pro 12×50.

 

So, both binoculars have the same exit pupil which is 4.1 but Vortex has wider field of view which is 5.2 compared to Levenhuk where angle of view is 4.7.

 

Leupold BX-4 Pro Guide HD 12x50mm has angle of view 5 degrees which is close to Vortex with angle of view 5.2.

 

  Leupold BX-4 Pro Guide HD Binocular, 12×50

Wide field of view, (field of view 5 degrees)
Magnification power 12x
Fully multi-coated high quality optics
80% Customer satisfaction
Price: $654.99

Leupold BX-4 Pro Guide HD Binocular, 12x50

4,7 score

 

 

These two binoculars have wider field of view than other optical devices available on the market.

Maybe there are some other available too but I know only about these two.

From this we understand that field of view doesn’t depend on the size of an exit pupil of the binocular alone.

 

exit pupil

 

It depends on the construction of the binoculars prism.

I checked other manufacturers, such as Leupold and Maven but it looks like Vortex and Leupold offer the best binoculars with magnification 12x and wide field of view. And the price is pretty reasonable.

For binoculars with magnification 6x, 7x, field of view is normally between 6.5 – 8.5 degrees.

For magnification 10x field of view is between 5-7 degrees, and for binoculars with magnification 12x field of view is around 4.7 – 5 degrees.

For binoculars with magnification 20x field of view is between 2.2 – 3.2 degrees.

 

Magnification 20x and field of view

In binoculars with magnification up to 12x field of view is normally more than acceptable.

The issue starts when magnification increases, such as 16x, 20x, 25x or higher than that up to 94x manufactured by Oberwerk.

For example, with magnification 20x it’s technically difficult to get field of view fully clear and sharp.

In binoculars, such as

Levenhuk Bruno Plus 20×80 ( field of view 3.2 degrees),

Oberwerk 20×80 ( field of view 3.2 degrees),

Celestron 20×80 SkyMaster Pro High Power Astronomy Binoculars ( field of view 3.2 )  field of view is wider than in Pentax 20×60.

But only 85-90% of the image is clear and sharp.

Edges of the image are not so clear in those binoculars. Compared to those binoculars Pentax 20×60 has narrower field of view which is 2.2 degrees (still acceptable). Exit pupil is 3mm.

 

  Pentax SP 20×60 WP Binoculars
Bak-4 Prism
Magnification power 20
Customer satisfaction: 78%
Price: $239

Pentax SP 20x60 WP Binoculars

4,7 score

 

But the image is almost 100% clear and sharp in Pentax 20×60. That’s why I chose Pentax.

So, it’s a matter of personal preference which one you want to choose. Because when it comes to high power binoculars field of view is not so critical.

Image quality is what matters.

Also, make sure to choose binoculars with fully multicoated lenses because only such binoculars produce high quality image.

Also, the difference of Pentax from other high power binoculars is that it is lighter. Its lens size is 60mm while in other high power binoculars mentioned above this size is 80mm.

 

Extra wide field of view binoculars

There are binoculars with extra wide field of view that gives you a completely different experience. They have field of view as much as 17 – 18 degrees.

This is simply fantastic. But magnification is limited by 4x.

This magnification is not as powerful as 8x or 10x but it’s very well compensated by extra wide field of view of the binocular.

Here I can recommend two such binoculars.

 

 

  Bushnell Spectator 4x30mm Extra-Wide Compact Binoculars
Extra-wide field of view binocular
Magnification power 4x
Field of view is amazingly wide
BaK-4 prism
84% customer satisfaction
Price: $47.95

bushnell extra wide

 

4,8 score

 

 

 

 

 

  Orion 4×21 Super-Wide Angle Binoculars
Extra-wide field of view binocular
Magnification power 4x
Field of view is amazingly wide
BaK-4 prism
100% customer satisfaction
Price: $67.27

orion extra wide field of view

4,8 score

 

 

I hope my guide about binoculars field of view was helpful. Just remember that binoculars with wider field of view are more pricey.

If you wish to find the best pair of binoculars for you with a nice magnification and wide field of view and need my help just show me a message and I will gladly help you.

 

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