Introduction: How to Build a Refracting Telescope

As of late, I've become very interested in space, stars, galaxies, and the universe. Naturally, then, I decided to build a refracting telescope for the creative project in a class I'm taking called "Changing Views of the Universe". 

I'm actually pretty pleased with my build. I ended up getting a good amount of magnification and I can see craters on the moon in an urban area (Washington, DC). Sadly, there were several things that could've been done much better with more time. I encourage anyone interested in building a telescope to check out my process and modify it as they see fit!

Anyway, let's get started!

What you'll need:

1. Two lenses of different magnification. I got one out of a handheld magnifying glass (the smaller in size lens) and from a scientific equipment shop. Make sure the larger diameter one also has larger magnification power. 

2. Two lengths of PVC pipe. I used a meter of 3" diameter pvc and a half meter of 2" pvc (I think). The smaller diameter PVC fit nicely inside the larger one, and, with a little finessing, the lenses fit in each. Make sure each length of PVC is a bit greater than the focal length of the lens.

3. Gaffers Tape. Gaff, Gaft, whatever. It's that wonderful black tape that's super easy to tear, doesn't leave marks, and isn't very shiny.

4. Flat black spray paint.  


1. Exacto knife
2. Dremmel 
3. Hot glue gun

Let's do it!

Step 1: Get Your Lenses Out!

If you're using a lens from a magnifying glass, get it out using the exacto knife and dremmel. Try to keep the lens from being cut or scratched... things won't look as good later!

Step 2: Paint It!

The first step is going to be painting. Cover the two lengths of PVC with black spraypaint, and even do the inside. Let it dry for a while... you don't want it to be at all wet for the next step. Make sure that the spraypaint you're using works on plastic.

Step 3: Tape It!

I actually made the mistake of putting the entire thing together without this initial step, and I regretted it quickly. PVC, even with spraypaint, is really reflective. We don't want internal reflection. The fact that my pipes were pretty small didn't help either. 
Ultimately, I decided that I'd tape the inside of the larger pipe. It's surprisingly easy to do, too. Thread a piece of gaff tape down the pipe and affix it to the edge on opposite sides. Using the smaller pipe that you bought, flatten the tape against the inide of the PVC by sliding the small pipe down the larger one. Make sense? good. Now do that a few times to completely cover the inside.

Step 4: Cut Cut Cut

Cut the larger tube to be about 3/4 the focal length of the powerful lens. The smaller diameter tube should be about double the size of the larger tube that you just cut off. This is going to be really helpful when you focus your telescope.

Step 5: Affix the Lenses

Hopefully, your internal diameter and larger lens diameters match up pretty nicely. If they're a little off (mine were) use gaffers tape to make the internal diameter smaller, rest the lens on the end of the pipe, and hot glue it in place using a low heat hot glue gun.

For the smaller lens, cut a hole into a pill bottle cap or some other plastic thing that fits nicely into the smaller diameter PVC. Hot glue your lens in the holder, and stick the holder into the telescope.

Step 6: Tape Tape Tape.

Finally, you're going to want to tape the rim of the smaller tube to ensure it doesn't fall into the larger one. I used a few strips of gaff tape that I stripped down the middle. It worked quite nicely!

Step 7: You're Done!

Go check out the moon, the stars, or even a planet! Thanks for reading, feedback is appreciated!