to a large extent, a telescope is only as good as its tripod and mounting.
a telescope magnifies everything, including vibration. that's why many telescopes
with decent optics are rendered useless when supplied on a cheaply made
mount. the mount's adjustments should be smooth, yet precise, as you'll
be using them to track the slow and steady apparent movement of stars. smooth
and precise movements - and a motor drive - are an absolute requirement
a telescope mount has two functions - (1) provide a system for smooth controlled
movement to point and guide the instrument, and (2) support the telescope
firmly so that you can view and photograph objects without having the image
disturbed by movement.
there are two major types of mounts for astronomical telescopes: altazimuth
- the simplest type of mount with two motions, altitude (up and
down/vertical) and azimuth (side to side/horizontal). altitude
and azimuth - thus the name altazimuth . good altazimuth mounts
will have slow-motion knobs to make precise adjustments, which aid in keeping
tracking motion smooth. these type mounts are good for terrestrial observing
and for scanning the sky at lower power but not for deep sky photography.
certain altazimuth mounts are now computer driven and allow a telescope
to track the sky accurately enough for visual use but not for long exposure
- a newer, modified version of the altazimuth
mount is called the dobsonian mount. the dobsonian mount was invented in
the 1970's by john dobsonian. a dobsonian mount is mounted on the ground
by a heavy platform. a dobsonian mount was designed to support massively
sized newtonian reflectors and keep a steady image from the size and weight
of the optical tube. it is common for dobsonian telescopes to have very
large apertures - anywhere between 6 and 20+ inches!
- superior to non-computerized
altazimuth mounts for astronomical observing over long periods of time and
absolutely necessary for astrophotography. as the earth rotates around its
axis, the stationary stars appear to move across the sky. if you are observing
them using an altazimuth mount, they will quickly float out of view in both
axes. a telescope on an equatorial mount can be aimed at a celestial object
and easily guided either by manual slow-motion controls or by an electric
motor drive to follow the object easily across the sky and keep it in view
of the telescope. the equatorial mount is rotated on one axis adjusted to
your latitude and that axis is aligned to make it parallel to their earth's
axis, so that if that axis is turned at the same rate of the speed as the
earth, but in the opposite directly, objects will appear to sit still when
viewed through the telescope.
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there are two basic types of equatorial mounts
equatorial mount - both newtonian
reflectors and refractor telescopes normally use this type mount. a large
counterweight extending on the opposite side of the optical tube is its
distinguishing feature. the counterweight is needed to balance the weight
of the optical tube.
mount - most catadioptric
and other shorter optical tubes use this style mount, which is generally
more convenient to use than the german mount, especially for astrophotography.
a more recent state-of-the-art computer controlled telescope allows fully
automatic operation making it extremely fun and easy to locate objects while
saving the observer considerable time and effort.
unless the telescope is a tabletop model, it should be set on a tripod or
pier-type platform. these must be rigid and minimize vibration. they should
be portable and lightweight as well as easy to handle and set up. appearance
can be deceiving, as bulk and weight are not as important as a well-engineered
tripod or pier.
mounts - "go-to" telescopes
now many telescopes feature computerized electronic
mounts with features that will automatically located and track objects in
the sky. these telescopes automatically take you to thousands of objects
in the sky and can even give you a guided tour! for more information see
our article on
computerized goto telescopes and gps telescopes at
(link to goto page at www.telescope.com).
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credits - "telescope 101" from