How to Build a Newtonian Telescope

If you love viewing the stars and are interested in telescopes then you will love the fact that you can actually build your on Newtonian telescope. These types of telescopes feature a relatively simple design that makes them super fun and easy to build on your own. In fact, Newtonian models are virtually the simplest type of telescope you can find.

The Newtonian model of telescope is a type of reflector telescope. The design of this type of telescope incorporates just two mirrors and a single eyepiece which makes it very friendly for building purposes. The primary or large mirror is a concave mirror. This concavity allows it to take the light that makes contact with it on its large surface and then focuses that light down to a very small spot within the telescope. In the Newtonian model the primary mirror is situated at the bottom of the telescope’s tube. The tube of this model essentially holds all the parts of the telescope together.

You will need the following items to make your Newtonian model:

4.5" F/8 36" focal length primary mirror with an adjustable mount
secondary mirror with mount
spotting scope (initial object finder)
Reflector focuser assembly
25 and 12.5 mm focal length PLOSSL eyepieces
4 to 6 foot 6" diameter PVC pipe
6" diameter PVC pipe cap or similar lens cap
several standard nuts and bolts
tripod

If you’re looking for the simplest approach to making your own then you can simply purchase these primary and secondary mirrors at a relatively low cost. However, those of you who are looking to build your telescope completely from scratch can actually make your own mirror, too. Use two pieces of round glass; one as a mirror blank and the other as a tool. Situate the mirror blank on top of the tool mirror. Place a mixture of water and grinding compound between them. You will then push the mirror blank across the tool mirror until it extends over the bottom mirror by approximately one-third of the diameter. Stroke the mirrors across each other until you’ve created the concave surface necessary for image reflection.

You will glue the mirror inside the PVC tubing with the reflective surface facing the other end. You will then mark the tube several inches down from the mirror. You will then cut two several small holes to place the spotting scope into. After that, roll a small magnifying glass inside a cut cardboard tube and slide it into the tube but make sure you can move it for spotting adjustment.