The Astronomers' Tools Optical Telescopes : With these telescopes, light is either collected by a lens system as in the Museum's refracting telescope or by mirrors as in a reflecting telescope, or a combination of both.
(light; is; either collected by a lens system as in the Museum's refracting telescope or by mirrors as in a reflecting telescope, or a combination of both) (light; collected; by a lens system)
light light
is collected
either collected by a lens system as in the Museum's refracting telescope or by mirrors as in a reflecting telescope, or a combination of both
by a lens system