Assertion: eyepiece | /r/HasAspect | a rubber eyecup
Facets:
Source sentences:
text: (glasses wearers are laughing about now)?First, if the eyepiece has a rubber eyecup, fold it up to its maximum height.
text: Manufactures now often produce eyepieces having rubber eye-cups that serve both to position the eyes the proper distance from the front lens, and to block room light from reflecting off the lens surface and interfering with the view.