Assertion: eyepiece's diameter | /r/HasProperty | aperture
Facets:
Source sentences:
text: In reality, the diameter (aperture) of a telescope determines its power and different eyepieces are used to get the best view of a given object.
text: The diameter of the objective is referred to as the aperture; it typically ranges from a few centimetres for small spotting telescopes up to one metre for the largest refractor in existence.