What are the uses of binoculars

Binoculars: structure and functionality

Telescopes and binoculars have been of invaluable service to mankind for centuries, whether when discovering distant coasts, hunting in the local forest, hiking or observing animals: With the targeted bundling and guidance of light beams, the optical devices enable distant objects to enlarge and view in detail. The enlarged image is created by the interaction of the objective, the lens system and the two eyepieces. Most binoculars are binocular, so each eye has its own eyepiece.

This is how the enlarged image is created

The lens consists of one or more lenses that capture the light and create a mirror image that is upside down. Many binoculars have two, high-quality, up to five lenses that work together. About the Prism system (angular glass body) inside the binoculars, the image is transferred back into the correct orientation. The two widespread prism systems include the classic Porro and the newer roof prism system. The two eyepieces usually consist of three to six lenses that act like a powerful magnifying glass.

Binoculars: The most important key figures

Every pair of binoculars has a performance specification in the form of “number x number”, with the first value being the magnification factor. Typical values ​​are 8 and 10: At 10x magnification, an object 400 meters away and viewed through binoculars appears to be only 40 meters away. Most small binoculars such as opera binoculars magnify by a factor of three, while those used in astronomy magnify significantly more by a factor of up to 50.

The second number indicates how many millimeters the lens diameter is. The larger the lens, the more light gets into the binoculars, which is of particular interest when looking at twilight. In order to be able to see well through the binoculars in poor lighting conditions, the lens diameter should be at least 56 mm. Night vision binoculars use residual light amplification or convert the invisible infrared light (thermal radiation) into image signals.

From telescope to binoculars

While telescopes or telescopes were used over 400 years ago, the first binocular variants for hand use were available from around 1823. The term 'binoculars', which is still in use, comes from its use by the military. With many models, the eyepiece can be set to the desired distance by turning it so that everything in this area can be seen in sharp resolution. There are now countless variants, including more and more digital binoculars.

The variety of products is great

The different prism systems each have their own advantages and disadvantages. In addition, the intended use is decisive; for example, different binoculars are used at sea than in open terrain. If you want to use your binoculars in a targeted manner, there is no avoiding detailed product advice from specialist retailers!

Other important binoculars features that influence the purchase decision are twilight number and light intensity (important for seeing in twilight), as well as the depth of field: the higher the magnification of the binoculars, the more precisely you have to adjust to get objects at different distances sharply resolved to recognize.

Attention: binoculars for spectacle wearers have optimized eyepieces for this!