Assertion: eyepiece's length | /r/HasProperty | measured
Facets:
value: from inside the barrel
type: OTHER
value: from the main lens
type: OTHER
value: from mirror
type: OTHER
Source sentences:
text: The focal length is measured from the main lens (or mirror) to where the light converges to focus.
text: This is because objective lenses are made of a combination of lenses and the focal length is measured from inside the barrel.