Assertion: telescope's mirror | /r/HasProperty | expensive to make
Facets:
value: much
type: DEGREE
Source sentences:
text: Because a mirror is less expensive to make than a complex group of lenses reflectors offer the biggest 'bang for the buck' in terms of aperture and as a result are much favored by amateurs especially for deep sky observing of galaxies and nebula.
text: Mirrors are therefore much less expensive to produce.