Galilean binoculars - Galilean binoculars

...Another feature is that, because binoculars are viewed with both eyes at the same time, they are easier to see and less tiring than monoculars. A relatively simple type is called Galilean binoculars, which, like Galilean telescopes, combine a convex objective lens and a concave eyepiece lens, with the distance between the objective lenses equal to the observer's pupil distance. This type has a somewhat narrow field of view, but because it does not use a prism, it is lightweight and is often small and has low magnification, and is used for opera glasses, etc. ...

*Some of the terminology used to refer to "Galilean binoculars" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…また両眼で同時に眺めるため，単眼の場合に比べ見やすく，疲れにくいことも特徴である。比較的簡単なタイプはガリレイ式双眼鏡と呼ばれ，ガリレイ式望遠鏡と同じように凸の対物レンズと凹の接眼レンズという組合せで，対物レンズの間隔は観察者の瞳孔間隔に等しい。この方式は視野はやや狭いが，プリズムを用いないため軽量であり，小型低倍率のものが多く，オペラグラスなどに用いられる。…

※「ガリレイ式双眼鏡」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報