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Telescope Guide

Refractor

This is a telescope constructed with a Galilean lens system. These telescopes are able to produce images with a greater degree of detail and contrast and are, therefore, particularly suited for observing astronomical objects like the stars and planets. They are also used for terrestrial observation.

REFRACTOR OPTICAL CONSTRUCTION     

Reflector or Newtonian

This is a telescope constructed with a Newtonian mirror system. It has its main advantage in a greater luminosity which gives it the capacity to observe weaker astronomical objects like nebulas and galaxies. The greater the aperture, the greater the field of view and the capacity to absorb light which helps in the observation of deep sky objects with low light emission.
High image luminosity is very important for astronomical photography.

NEWTON OPTICAL CONSTRUCTION 

Cassegrain

With equal aperture, these telescopes have a smaller size and weight than Reflectors or Newtonian Telescopes. The Cassegrain consists of a parabolic mirror with a hole in the centre and a small convex secondary mirror with a hyperbolic shape, aligned with the primary mirror. The luminous rays reflected from the primary mirror converge on the secondary mirror, and are reflected again towards the primary mirror through the central hole, coming into focus on the focal plane on the other side of the hole. Two different
versions of the Cassegrain system are called the MAKSUTOVCASSEGRAIN and the Schmidt Cassegrain. The optical pattern of these two telescopes are similar, the main difference the presence of a lens that closes the mouth of the telescope, supporting the secondary mirror.

 

 CASSEGRAIN OPTICAL CONSTRUCTION

Choosing A Telescope

In choosing a telescope it is important to bear in mind it’s intended use. Also taking into account the size and manageability of the instrument.

FORSEEN USE	SUGGESTED MODEL
Terrestial view observations of planets and stars	Refractor Maksutov-Cassegrain
Observations of galaxies and nebulas, Deep sky objects	Newtonian Maksutov-Cassegrain
Photographic observations	Newtonians with motor