Binoculars are made of two mirror symmetrical telescopes, situated next to each other and arranged so that they point accurately in the same direction.
This means that you can use both eyes when you look at objects in the distance.
As compared to a monocular telescope, you don't need to close one eye to get a clear view.
Because of this, you get a three-dimensional image with depth perception.
Common optical parameters Binoculars' magnification is determined by the length of the eyepiece divided by the central distance of the object.
For example, if magnification is five times' normal, the image appears five times closer than it really is.
Most hand-held binoculars use less than this.
Binoculars are categorized based upon the magnification they produce times the objective diameter, which is expressed in millimeters.
The field of view is the distance in width visible at 1000 yards or the number of degrees able to be viewed.
The optical design used in a particular binocular determines what the field of view is.
Different optical designs Many early binocular telescopes used Galilean optics.
Galilean optics uses a concave eyepiece lens along with a convex objective, which produces an upright image.
One disadvantage to this type of construction is that view is constricted and the user cannot adjust in extremely high magnification.
Porro prism binoculars use a double prism shaped like a "Z" to produce the reflection.
Italian optician Ignazio Porro's discovery was patented in 1854.
It allows for a shorter binocular and greater depth perception because the objectives are more broadly spaced.
Achille Victor Emile Daubresse designed binoculars that used roof prisms in 1880.
Most of these types of binoculars use the Abbe-Koenig prism or the Schmidt-Pechan prism.
These types of prisms usually do not require realignment.
Practical applications Astronomy has been using binocular telescopes for many years.
In general, observing the heavens would be almost impossible without the telescopes and binoculars astronomers use.
Yet, with these tools, many throughout the world enjoy phenomena such as supernovas and comets.
Binoculars applications also are a great attraction for tourist spots and destinations.
Tourists can use coin-operated binoculars to give visitors a closer look at their surroundings for a few minutes.
Binocular telescopes are also useful to a variety of outdoor activities such as observing the environment, watching birds, or even hunting.
Those who engage in these activities understand how important the functionality and dependability of the binoculars is.
Indeed, some of these activities would not be possible without using binoculars.
In addition, the armed forces, such as the Air Force, Navy and Army, also use binoculars to help keep safety and security in force.
During battles, their use of binoculars can save lives and actually help troops conquer the enemy.
With binoculars, they can also monitor activities, track enemies, and thwart surprise attacks.
Even though binoculars may have improved since their first discovery, their applications remain in valuable in a variety of circumstances.
They should not be considered simply equipment used to view objects, but as truly valuable instruments that have been tested and refined over hundreds of years.
When you buy your own, it can be very useful to you during a trip, just as your camera is.