Assertion: eyepiece | /r/HasAspect | focal length
Facets:
value: usually
type: TEMPORAL
Source sentences:
text: The eyepiece has a focal length indicated in millimeters.
text: Eyepieces have focal lengths, too —
text: Eyepieces usually have their focal length marked on the piece.
text: Eyepieces also have focal length, which lets you know the magnification the eyepiece offers you.