Meade Instruments pmn - Manual (Page 14)

Types of Telescopes
All telescopes fall into one of three optical classes.
Refracting Telescopes, like
the Meade Model NGC-70,
use a large objective lens
as their primary light-
collecting element.
Meade® refractors include
achromatic (2-element)
objective lenses in order to
reduce false color that
results when light passes
through a lens.
Reflecting Telescopes use
a concave primary mirror
to collect light and form an
image. In the Newtonian
type of reflector telescope,
the Meade Model DS-
2130ATS, light is reflected
by a small, flat secondary
mirror to the side of
the main tube for
observation of the image. This is a large telescope
for a comparatively low price.
Catadioptric (Mirror-Lens) Telescopes like the
ETX-90 employ both mirrors and lenses, resulting in
optical configurations that achieve remarkable
image quality and resolution in extremely short,
highly portable optical tubes.
TYPES
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