Optical field of view (FOV) refers to the width of the area that you can see when looking through a pair of Binoculars
or a Spotting Scope
, quite simply, how wide an area you can see through your optics. Field of view is usually described in terms of 'linear field of view' or 'angular field of view'. Both figures essentially indicate that the field of view of the optic is a certain width, but they just use different numbers to describe this.
Linear field of view is also known as the true field of view and indicates the width (in m) of the area that you can see when standing 1,000m away from an object.
Angular field of view is also known as the apparent field of view and refers to the true angle (in degrees) seen through the optics.
It is easy to convert between the two field of vision measurements:
To convert an angular field of vision to a linear field of vision, simply multiply the angular field of vision by 52.5.
To convert a linear field of vision to an angular field of vision, simply divide the liner field of vision by 52.5.
When choosing your binoculars or spotting scope, take some time to consider where you are planning to use them, as this will indicate the most suitable field of view required to get the most out of your product. The most important thing to remember is that the larger the number is given to the field of view (FOV), the larger the width of the area you will be able to see through your scope. A larger field of view is desirable if you are planning to use your scope to watch anything that is moving quickly across your viewing area as it will make it easier to aim and stay on a moving subject. For this reason, scopes with a larger field of view are favored by people watching birds in flight, a ball at a cricket game, an athlete in a race or views from a moving car.
Don't forget field of view (FOV) and magnification are closely linked, with higher magnifications resulting in a smaller field of view. Take some time to consider whether you wish to view your subject in great detail, or would prefer to be able to keep track of it if it is moving quickly; after all, there's no point being able to see the fine detail on a bird's feather if you can't find the bird in the first place!