Binoculars Field Of View Explained (With Linear & Angular FoV Converters)
In a nutshell the field of view (FoV) is what you can see through the lens from edge to edge. So that’s everything you can see through the lens from left to right and everywhere in between. But as with most things, there’s more to it than that. There’s the eyepiece, position of the lenses, how thick they are, the way they’re assembled and the magnification, all contribute to how the FoV comes together. So let’s get into the FoV of binoculars.
Table of Contents
How Is The Field Of View Measured?
The field of view is stated by the manufacturers in a couple of ways. Binoculars, spotting scopes and rangefinders measure the FoV in metres per 1,000 metres, but rifle scopes are measured in feet per 100 yards. Binocular manufacturers either use metres per 1,000 metres or as a degree.
Linear Field Of View
When manufacturers quote the linear FoV they are referring to metres per 1,000 metres, like 131 metres per 1,000 metres – it means that at 1,000 metres distance you can see 131 metres from side to side.
Angular Field Of View
If you see angular FoV on the description followed by something like 6° that means you can see 6 degrees width through the lenses. The higher the angle quoted depicts a wider field of view. To convert the degrees into metres per 1,000 metres just multiply the number of degrees by 17.5. This is because 1° is equal to roughly 17.5 metres. So to convert 8° into metres per 1,000 metres just multiply by that amount to calculate the linear FoV.
So 8° angular is equal to 140 metres per 1,000 metres linear.
Binocular FoV Calculators
Angular To Linear FoV Converter
Enter the angular field of view into the box below to work out the linear field of view
Linear To Angular FoV Converter
Enter the linear field of view into the box below to work out the angular field of view
Field Of View, Eye Relief And Magnification
Pretty much every feature to do with optics are linked to other features in some way. It sounds pretty complicated but once you get your head around it, it all becomes clear.
What Has Eye Relief Got To Do With FoV?
It’s all about your positioning really, if you are too close to, or too far away from the eyepiece, your FoV will be affected. You might see the FoV slightly shaded or shadowed, or “clipped” this is called vignetting. So to get a clear image and to see the full FoV, you need to have the correct eye relief.
What Is Eye Relief?
Put simply, eye relief is the correct distance between your eyes and the eyepiece. Having the correct eye relief will allow you to see the whole image and the full FoV. It is always given by the binocular manufacturer and the best eye relief is somewhere between 14 to 18mm.
What’s Magnification Got To Do With The Field Of View?
There is a direct relationship between the FoV and the level of magnification. It works like this, the higher the magnification, the lower the FoV. It’s fairly obvious when you think about it, as you close in on the object, you lose a great deal of the surrounding features.
As Magnification Increases – The Field Of View Decreases
That’s it, in a nutshell as we said at the beginning, no fancy technical terms to cloud your mind. Just simple straight to the point explanations.
A Summary Of The Field Of View Of Binoculars
- The field of view (FoV) is the image you can see through the lenses of binoculars from one side to the other.
- The FoV is measured either as an angle (angular FoV) or as metres per 1,000 metres (Linear FoV).
- To convert the degrees to metres per 1,000 metres multiply by 17.5 because 1° is equal to 17.5 metres.
- Eye relief is the perfect position of the eye to the eyepiece. If you don’t have the correct eye relief your FoV will be affected.
- The magnification of your binoculars affects the FoV. The closer you zoom into an object the less of the FoV you can see.
- As magnification increases – the field of view decreases
Frequently Asked Questions
A good field of view is anywhere between 91 to 115 metres per 1,000 metres for binoculars.
FoV at 1,000 yards is the linear measurement of the Field of View, it is usually expressed as either feet per 1,000 yards or as the angular measurement in degrees. So 315 feet at 1,000 yards means that you can see a field of view of 315 feet wide at a distance of 1,000 yards.
The magnification affects the FoV, as the magnification increases, the FoV decreases.
The opposite is true, the field of view decreases as magnification increases.