Assertion: close lens | /r/HasProperty | specified by their optical power
Facets:
value: often
type: TEMPORAL
value: in diopters
type: LOCATION
Source sentences:
text: Close-up lenses are often specified by their optical power in diopters, the reciprocal of the focal length in meters.
text: Close-up lenses are usually specified by their optical power, the reciprocal of the focal length in meters.