Assertion: telescope's lense | /r/HasProperty | convex
Facets:
Source sentences:
text: Refracting telescopes use convex lenses, at the front of a tube, to gather and focus incoming light.
text: Refracting telescopes have two convex lenses on either end of a long tube.
text: Johannes Kepler first explained the theory and some of the practical advantages of a telescope constructed of two convex lenses in his Catoptrics (1611).