The telescope is an optical instrument that allows you to observe distant objects with much more detail than with the naked eye. The word telescope is made up of the Greek root “tele”, which means far, and the suffix “scope”, which means to see.

The invention of the telescope is attributed to the German lens maker Hans Lippershey in the year 1608. Subsequent investigations have determined that it was Juan Roget, a native of Gerona, who first built a similar device in the year 1590.

Galileo Galilei, hearing about the invention, decided to build one on his own. In 1609 he presented his version, which is considered the first astronomical telescope.

Telescope characteristics

Telescopes can be of various types, from the simplest for personal and recreational use to the most complex used in large observatories. However, they all share certain common characteristics, which are the following:

  • Objective lens: the final lens of the telescope, located at its end.

  • Focal length: length that separates the main lens from the focus or objective.

  • Limit magnitude: represents the limit of the observable, and is calculated according to a certain formula.

  • Magnification: This is the number of times the telescope magnifies the object being viewed, based on the ratio of the focal length to the eyepiece.

Types of telescope

There are two main types of telescope:

  • Refractor telescope: uses a centered optical system, capturing images through several converging lenses that distort light, according to the refraction principle.

  • Reflector telescope: uses mirrors to reflect light instead of lenses. It generally uses two mirrors, primary and secondary.

There is also the so-called catadioptric telescope, which is a mixture of the previous two, since it uses both optical lenses and mirrors. Some may use three mirrors instead of two.

Parts of the telescope

Commonly telescopes are made up of several parts, which are:

  • Objective: it is the final lens of the telescope, where the light enters.

  • Ocular: the amplifying lens, which brings the image to the eye.

  • Barlow lens: lens that allows the observed image to be amplified.

  • Filter: allows to improve the observation, by slightly opaque the image.

  • Mount: structure that physically supports the telescope.

  • Tripod: stabilizing element of the telescope.

Telescope operation

Telescopes work in a similar way to how the human eye operates, and in fact their principles are based on those of this organ. The eye is made up of two parts: the pupil, which has the function of a lens, and the retina, which reflects the light that is perceived.

When looking at a very distant object, the pupil can perceive only very little light, which causes a very small image to be reflected on the retina. At a shorter distance from the object, the amount of light perceived by the pupil will be greater, which causes a larger image to be reflected on the retina.

In the case of the refracting telescope, it uses its main lens to capture a greater amount of light, which when focused allows a larger image to be produced in the second lens, which fulfills the function of the human retina.

Instead of using lenses, reflecting telescopes use mirrors, which focus the light on a single point, reflecting the light instead of refracting it. This allows the amplification of the perceived image to be even greater, which which translates into greater power or range.

How do you calculate the magnification of a telescope?

The lenses of the telescope have a magnification that is represented by a number accompanied by an “x”. For example, if a lens has a magnification of 10x this means that if the object observed is 100 meters away, with this lens we will perceive it as if it were only 10 meters away.


Leave a comment

Please note that comments must be approved before being published.