How Far Can You See With 12×25 Binoculars?
There are several factors that determine how far a pair of binoculars can see. With the right binoculars, you can see celestial objects hundreds of thousands of miles away, and you can also see animals a few miles away. A pair of 12×25 binoculars falls in the class of compact binoculars, because the objective lens is less than 30mm (25mm). Factors such as atmospheric conditions, the weather, and brightness will affect how far you can see with the 12×25 binoculars.
At 12x magnification, this pair of binoculars brings the image 12 times closer than an unassisted eye would. Because the magnification of this pair of binoculars is higher than 10x, it makes steady viewing a challenge. If you are moving, such as on a boat or in a moving vehicle, the binoculars might not be steady enough to allow you to view far away images.
Field of View
Field of view refers to width at a distance. For example, if you are pointing the binoculars at something 1000 yards away, you can see an image through them that is 90 feet wide, but anything wider than that you wouldn’t be able to see. Higher magnification means a smaller field of view. At 12x magnification, the field of view narrows significantly, making it difficult to locate small and mobile objects when you are scanning from hundreds of kilometers. The eyepiece design plays a role in determining the field of view as well.
The Diameter of the Field of Objective Lens
The 12×25 binoculars are generally small and light, and fit in small backpacks. However, with the diameter of the objective lens at 25mm, the binoculars limit the amount of light that gets in through the optics. There are binoculars with diameters bigger than 40mm, making them show brighter images than the 25mm unit. However, some 25mm binoculars have high-quality optics that provide bright images even with the small objective lens.
The size of the exit pupil is the result of dividing the diameter of the field of view by the magnification. For instance, with the 12×25 binoculars, the size of the exit pupil is approximately 2mm. This is low compared to a pair of 8×42 binoculars whose exit pupil is 5.25mm. This number indicates the size of the shaft of light that gets to your eye. The exit pupil also determines the amount of light that gets through the optics. A higher number means brighter images, which is especially useful in low-light conditions. A higher number also means that the object will still be bright, even if your hand shakes.
The pupils of your eyes will vary between 2mm in bright light and 7mm in a dark setting. In dim lighting, the 12×25 will not let you see far because the exit pupil is smaller.