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How to Build a Simple Reflecting Telescope

A good reflecting telescope can be expensive to buy. The cheapest reflectors cost hundreds of dollars, and it is easy to spend thousands of dollars on high-quality models. A cheaper alternative is to build your own reflecting telescope. Using materials mostly available at a hardware store and spending less than $200, you can build a Newtonian telescope. This classic telescope, first developed by Isaac Newton hundreds of years ago, offers both a simple design and impressive views of the night sky.

Things You'll Need

Concave mirror
Tube
Ruler
Small diagonal mirror
Mirror mounts
Screws
Adjustable eyepiece tube
Eyepiece lens
Adhesive

Instructions

- 1
  Choose a concave mirror. All parts of the telescope will depend on your concave mirror. Larger mirrors collect more light, but smaller mirrors are easier to work with and do not need to be as perfect.
- 2
  Find the concave mirror's focal length. The focal length is equal to half of the mirror's radius of curvature. Most commercial mirrors list the focal length on the mirror's packaging.
- 3
  Determine the tube size you need. The diameter needs to be the right size to accommodate the concave mirror securely, and the length of the tube should be longer than the mirror's focal length.
- 4
  Mount the concave mirror at the bottom of the tube, opposite the end that will be open to the light. Hold the mirror with a mount screwed into the tube.
- 5
  Insert the diagonal mirror. A spider mount is best to hold the diagonal mirror in the center of the tube. Place the mirror above where you will have the eyepiece exactly at the focal point of the concave mirror.
- 6
  Align the diagonal mirror. When you look through the eyepiece hole, you should clearly see the image reflected from the concave mirror.
- 7
  Attach the eyepiece tube and lens with adhesive. Use a sliding plumbing tube to be able to adjust the eyepiece focus. Insert and attach the lens to the top of the eyepiece.

Astronomy