The Lens Polisher's Workshop

The following are instructions for the construction of a simple telescope. This is a telescope employing two converging lenses, which differs from Galileo's telescope. This type of telescope, with two central lenses, provides an upside-down picture. More sophisticated telescopes include prisms which turn the picture again, providing a straight image. In Galileo's telescope (which included one diverging lens and one converging lens) the image was first received with the proper side up.

Tools and materials :

  1. One converging (magnifying lens) 3-5 cm. in diameter, with a focal distance of about 15 cm.
  2. One converging lens whose diameter is smaller than that of lens no. 1 and whose focal distance is about 2-4 cm.
  3. Two thick paper squares, 15 x 15 cm.
  4. A thick paper rectangle, 10 x 20 cm.
  5. Transparent sticky tape.
  6. Some putty.
  7. Glue.
Construction process:
  1. Use the paper squares to create two cylinders identical in diameter to the lenses in your possession. Tape the edges. (Make sure the diameter of one cylinder is somewhat smaller than that of the other cylinder, so that they slide into one another.

  2. Use the tape to stick each cylinder to its lens (you can use the putty to help you).

  3. Insert the narrow cylinder into the wider one, make sure that the lenses are distant from each other.

  4. Bring the telescope to your eye, so that the lens with the shorter focal distance faces your eye.

  5. Look at a distant structure or object through the telescope. Shift the lenses closer and farther from each other until the object is seen clearly and sharply. Tape the cylinders together.

You now created a simple telescope.
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