Newtontelescoop

A Newtonian telescope, also known as a Newtonian reflector or simply a Newtonian, is a type of reflecting telescope invented by English scientist Isaac Newton in 1668. It was one of the earliest practical telescope designs and remains popular today, particularly among amateur astronomers, due to its relatively simple construction and good performance for its cost.

The fundamental principle of a Newtonian telescope is the use of a parabolic primary mirror to collect and focus light. This primary mirror is located at the base of the telescope tube. Before the light reaches the focal point of the primary mirror, it is intercepted by a small, flat secondary mirror, which is positioned at a 45-degree angle to the incoming light. This secondary mirror redirects the light beam out of the side of the telescope tube, where an eyepiece is located. The observer then looks through the eyepiece to view the magnified image.

The advantage of the Newtonian design lies in its ability to avoid chromatic aberration, a common problem in refracting telescopes where different colors of light are focused at different points, resulting in color fringing. Reflecting telescopes like the Newtonian do not suffer from this issue. Additionally, Newtonian telescopes can be built with larger primary mirrors for a given cost compared to refractors, allowing for the collection of more light and the viewing of fainter objects. However, they can be prone to secondary mirror obstruction, which slightly reduces image contrast, and the observer's head can sometimes block incoming light.