Assertion: angle eyepiece | /r/HasProperty | developed
Facets:
Source sentences:
text: Beginning in the late 19th century, the requirements for the field of view of telescopes became increasingly stringent, particularly for military optical devices, such as field binoculars and periscopes; wide-angle eyepieces with a field of view of 65°–70° were developed.
text: Beginning in the late 19th century, the requirements for the field of view of telescopes became increasingly stringent, particularly for military optical devices, such as field binoculars and periscopes; wide-angle eyepieces with a field of view of 65°–70° were developed.