Below is a discussion of three basic components that are used
in conjunction with telescopes, to aid and enhance celestial observation of night skies.
Telescopic Mounts
Telescopes need to be supported by a mount in order to remain steady, point at the desired object, be adjusted
for movement caused by the Earth´s rotation, allow hands free changing of eyepieces and the undertaking of other essential
activities. The two basic types of telescopic mounts are alt-azimuth and equatorial.
Alt-azimuth mounts are similar to camera tripods with two axes of rotation, a vertical
axis (altitude) and a horizontal axis (azimuth). To locate an object, the telescope is rotated along the horizon (azimuth
axis) to the object's horizontal position, and then tilted along the altitude axis, to the object's vertical position. The
alt-azimuth is straightforward to use and is an excellent tool for beginners.
The use of this type of mount will help train
amateur astronomers to map constellations and track movements of the planets. The alt-azimuth mount, however, does not
smoothly track the motions of heavenly objects and is not at all suitable for celestial photography.
The other most typical telescopic mount is the Equatorial mount. This type of mount
also has two axes of rotation, polar and declination, which are aligned with the poles to track objects` motions. A common
type of equatorial mount is the fork mount – the base aligned with one axis of orientation and the forks with the other.
Equatorial mounts allow a telescope to smoothly follow the motion of an object across the heavens and are therefore
excellent for astrophotography. Motorised drives, now commonly and economically connected to this type of mount, facilitate
continuous tracking. Set up by simply typing in (to an on-board chip or connected PC) longitude and latitude, date and time,
you can thereafter select the object you wish to observe and the “driven” telescope will whir and point at the object of
desire.
Eyepieces
Eyepieces are lenses, or a combination of lenses, used to alter a telescope`s magnification, provide a
sharper image, allow comfortable eye relief and determine a telescope`s field of view. Eyepieces should be interchangeable
and are slotted into the eyepiece holder of a telescope. The choice and understanding of differing eyepieces is probably the
most joyous enhancement to a beginner`s observational skills. An eyepiece is the second lens in a refractor or the only
lens in a reflector telescope and may in itself be a combination of lenses.
Telescopes are usually provided with at least one basic magnification eyepiece/lens
but the must buy is a Barlow Lens. The Barlow fits between the eyepiece holder of the telescope and any other
supplementary eyepiece to amplify magnification 2x or 3x. It is the most cost efficient, additional component that an
amateur astronomer should acquire.
Filters
Filters, made from glass or plastic, are placed in the barrel of an eyepiece to restrict certain
wavelengths of light emitted from an object. They are most commonly used for safer observation of the sun, to contrast
details of the moon and planets, and to enhance and contrast details of fainter objects.
|
Planets: