|
|
Magnification - The linear magnifying power of binoculars. A magnification of factor 7, for example, produces an image as if one were 7 times closer to the object.
Objective Diameter – The diameter of the objective lens determines how much light can be gathered to form an image. It is usually expressed in millimeters.
It is customary to categorize binoculars by the magnification × the objective diameter; e.g. 7×50.
Field of View - The field of view of binoculars is usually notated in a linear value, such as how many feet (meters) in width will be seen at 1,000 yards (or 1,000 meters), or in an angular value of how many degrees can be viewed.
Eye-relief - Eye relief is the distance from the rear eyepiece lens to where the image is formed. The longer the focal length of the eyepiece, the greater the eye relief. Eye relief can be particularly important for eyeglass wearers. The eye of an eyeglass wearer is typically further from the eye piece which necessitates a longer eye relief in order to still see the entire field of view. |
 |
|
| |
|
