Individual Focus Binoculars
eyepiece of the binocular focuses independently of the other (unlike
with a center focus binocular which adjusts both eyepieces at the same
The light-gathering power of a binocular is determined by the surface area of its objective lens.
transmission describes the percentage of available light passing
through a binocular to the viewer's eye. Better coatings on the optics
of a binocular increase the amount of light that reaches the eye.
Higher magnification allows you to see more detail through the binocular.
Note: As the magnification of a binocular increases, the field of view decreases.
Binoculars with multi-coated optics have one or more surfaces coated.
Within a binocular the coatings may vary from one surface to another.
For example, one surface may not have any coatings, another may have
only one coating, while another may have several coatings.
atmospheric air within the binocular is replaced with nitrogen. This
prevents mold, mildew or acid etching of binocular lenses and prisms
that atmospheric air (containing moisture) would permit. Most
waterproof binoculars are nitrogen purged.
Temperature changes, elevation changes, or extreme humidity can create
internal fogging. Most of the time this moisture dissipates on its own
in a matter of minutes.