Unlock FREE Shipping When you Purchase $100+

Beginner Skygazer's Guide

While Galileo didn’t invent the first telescope (Thomas Harriot did), he was the first to derive results by confirming Copernicus’s Heliocentric Model.

The type of telescope he used was called the "Refractor". This is the simplest Telescope which uses a large lens known as the Objective on one end of the tube which focuses incoming light to a focal point near the other end. Rather than simply magnifying objects, a telescope’s main purpose is to act as a light funnel, focusing the few protons emitted by celestial objects and concentrating them for an eyepiece OR your camera’s sensor.

The objective brings the light to a fine point of focus called the “Prime Focus”.  When doing visual astronomy, which is to say, using an eyepiece, this is where you will want to line up the focal point of your eyepiece, NOT the eyepiece itself. On the other hand, when doing astrophotography, the “Prime Focus” is where you will place the camera’s sensor directly.

Reflector Telescopes

Revolutionary as they were, the original refracting telescopes had some pretty serious limitations. So in 1668 Sir Isaac Newton invented the first Reflecting Telescope (also known as the Newtonian Reflector Telescope) which used mirrors instead of a lens to bring the incoming protons to a “Prime Focus”.

In this type of assembly, light travels all the way down the tube to a concave mirror called the “primary mirror” which, like the lens in the refracting model, performs the function of collecting and concentrating the light. The light then travels back down the tube and, before reaching its “prime focus”, hits a flat mirror at a 45 degree angle called the “secondary mirror” which bounces the light out through a hole in the side of the tube where you find the Prime Focus. It is there that you would either place the focal point of your eyepiece OR your camera’s sensor.

 Other types of reflectors:

Classic Cassegrain

Light travels down the tube to a parabolic primary mirror at the back, much like in a Newtonian reflector; however, rather than the flat 45-degree secondary mirror, Cassegrain Reflectors use a convex mirror which sends the light back down to the back of the tube and through a hole in the primary where you find the focal point.

Maksutov Cassegrain

Instead of parabolic mirrors, these use Spherical mirrors which result in spherical aberration.  To compensate for this, they use corrector plates at the front end which bend the light just enough to correct for this spherical aberration.

Scmidt Cassegrain

Instead of parabolic mirrors, these use Spherical mirrors which result in spherical aberration.  To compensate for this, they use corrector plates at the front end which bend the light just enough to correct for this spherical aberration.