Assertion: telescope's lens | /r/HasProperty | concave
Facets:
Source sentences:
text: A reflecting telescope uses a concave lens and doesn’t have the same limitations as the refractors.
text: If a lens is concave or diverging, it takes parallel rays and bends them so that they spread out.
text: It consisted of a convex and concave lens in a tube, and the combination magnified three or four times.