Assertion: plössl eyepiece | /r/HasProperty | obscure idea
Facets:
value: until the 1980s
type: TEMPORAL
Source sentences:
text: The Plössl eyepiece was an obscure idea until the 1980s when cosmic hardware makers began selling overhauled adaptations of it.
text: The Plössl eyepiece was an obscure design until the 1980s when astronomical equipment manufacturers started selling redesigned versions of it.