The primary purpose behind the design of a binocular is to impart clarity to your outdoor observations. With so many specs around the corner, it does get a bit confusing to choose the best.
The best method of assessing the performance of your optical device is to look through its specs. Of course, this can be fruitful only when you what each spec and unit means.
To make a case for you, the field of view and magnification of your binoculars are the two most striking features. They impart quality and power to your outdoor viewing.
What is the field of view of a pair of binoculars?
If you have recently bought a pair of binoculars, you must be a little lost around the numbers. In reality, these numbers are much different from telescope or microscope units.
The two crucial factors for a pair of binoculars are its magnification and diameter of your objective lens. Magnification is also interchangeably used as ‘power.’
The diameter of the objective lens is expressed in milometers. The more significant is the amount of light ray collection, the higher is the diameter of the objective.
Bigger objective lens diameter is especially useful while viewing in low-light conditions. Larger objective lenses in your binoculars also offer a full field of view.
The Field of View of a Pair of Binoculars
The field of view is an essential factor while deciding on the specs of your Binoculars. The field of view is simply the width of the area that you observe through your binoculars.
The most significant advantage of a field of view is the ease of tracking objects without moving the device. This property is particularly useful for fast-moving objects such as birds.
The design of the lens of your telescope can primarily affect its field of view. It also depends on the diameter of the objective in terms of magnification.
The field of view of your telescope is calibrated either in degrees or feet. Typically, in most binoculars, the field of light falls within the range of 6 degrees to 7.5 degrees.
If you see two fields of view calibrations printed on your binoculars, do get confused. Often the manufacturer mentions the angular field of view and the linear field of view.
The angular field of view is the actual angle that you see through your binoculars. It is usually calibrated in degrees.
The linear field of view, on the other hand, is the actual width is seen through your binoculars. This is measured in feet.
The larger the angular or linear field of view is, the more significant in the area. If you have an angular field of view, it is easy to calculate the direct field of view.
You multiply the angular field of view with the units 52.5. This will convert the group in the degree to feet.
Your binocular’s field of view is closely related to its magnification. If you have a larger magnification, your field of view is bound to smaller and vice versa.
The eye relief in binoculars
If you purchase high quality binocular, you will most likely get an added feature called the eye relief. The maximum distance between your eye and the ocular lens is called eye relief.
It is important to note that the field of view should remain unaltered at an accurate eye relief. As you move the binocular farther, the image becomes smaller.
Until it almost feels like peeking through a tunnel. If you use glasses, you will have to place the binoculars at a larger distance than usual.
A sufficient eye relief, say of 14mm, will not blur the image or cut its edges. Many binoculars also sport rubber eyecups.
These eyecups act as an aid to reduce the distance from the ocular lens. The turn and slide mechanism further help in eliminating eye strain.
What are the applications of a full field of view of a binocular?
While viewing an object with an optical device, you can fit in more into the image with a more significant field of view. This is a highly coveted feature when it comes to activities like bird watching.
Bird watching binoculars are designed to have a lower magnification for a higher field of view. The only disadvantage of a larger field of view is decreased eye relief.
If you wish to achieve wider angles, you will have to reduce the magnification even further. This makes it clear that there will always be a disparity between magnification and field of view.
Reference
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