How to Make a Simple Telescope

Step 1Acquire a pair of lenses - a large convex lens and a small concave one. (Convex lenses are thicker in the center than at the edge; concave ones are thinner in the center.)

Step 2Find two cardboard tubes that will allow one to slide inside the other.

Step 3Figure out how far apart the lenses should be by looking through the smaller lens while holding the larger one out in front of you. When you can focus on an object in the distance, measure how far it is between the two lenses.

Step 4Double that measurement. The length of the two tubes should be about this long.

Step 5Fasten the larger lens on one end of the wider tube. Hot glue is good for this.

Step 6Mount the smaller lens at the opening of the smaller tube. This is the eyepiece.

Step 7Build a gasket from cardboard or Styrofoam if the tube opening is larger than the lens.

Step 8Make sure the lenses line up with each other. The centers should be in the centers of the tubes and the lenses should be parallel with each other.




Tips & Warnings
Magnifying glasses are convex lenses.
The best type of lenses are a low-power convex lens and a higher-powered concave one.
Ask at an optical shop for discarded lenses.
If you can't see anything or only pick up part of an object when looking through the telescope, check the lens alignment.
Don't look at the sun through these lenses.