How Binoculars Work - The Optical Mystery Explained
For those who have recently taken up a hobby requiring some sort of magnified optical function, such as bird watching or amateur astronomy, the first binocular purchase may be confusing. For many people this is simply because they do not know how binoculars work.
The Twin Telescope Advantage
The name ‘binocular’ derives from the Latin bi (meaning two) and oculus (meaning eye) and describes a hand held optical device whose function is essentially to magnify distant images using an eyepiece and so allow them to be examined in detail.
One of the easiest ways to describe a pair of binoculars, is to think of them as a set of adjoined, twin telescopes.
This is how binoculars work.
At the end of each telescope is a large optic lens, through which light passes, capturing the image much the same way as the lens of a human eye. In the case of binocularity though, the optic performs another function – to magnify the original images the light travels along the tube so that the image appears much larger and closer than it is. The addition of the second lens (at the eyepiece) ensures that the image is further magnified.
Because of the way the binocular lens operates this image at first appears upside down. In the case of field glasses, a second lens, further on in the chamber inverts the magnified image so that the optic result will always appear right side up.
By far the most popular binocular option these days however, are those utilising the prism method – in these cases a prism in each tube more accurately performs the work of the second lens and results in an even clearer optic result from your binoculars.
There are also various binocular options you can choose from including camera binoculars and oberwerk binoculars.