Newtonian Telescopes

General properties of Newtonian telescope

A Newtonian reflector is the most common and simple type of a reflecting telescope. It was invented by Sir Isaac Newton to fight chromatic aberration.

Newtonian refractor is one of the most popular telescopes on the market. Like all refractors, it can be used for all sorts of observations.

Optical design of a Newtonian telescope

Because of its low cost and simple design, it is great for amateurs and also professionals. Newtonian telescopes are often positioned on a Dobsonian mount.

The combination is trendy among amateur astronomers.

Newtonian telescope

Newtonian reflector (Available from:http://www.jb.man.ac.uk/public/im/newtonians.html. [accessed 29 Oct 2019] )

Like all reflecting telescopes, a Newtonian telescope features:

an open optical tube,
a concave primary mirror and
a diagonal secondary mirror.

Path of the light in a Newtonian telescope

Once the light enters the tube, it is reflected upwards to the secondary mirror, where it is directed out the side of the reflector to an eyepiece.

The eyepiece is located near the top end of the tube. A Newtonian reflector uses a parabolic shape of the primary mirror – it is free of chromatic aberration but suffers from a defect called a coma.