Main Tube of the Telescope

• To build a reflecting telescope, you will need a concave mirror which has some magnification like those found in bathrooms. Determine the focal length of the mirror. This can be done by taking the mirror outside and finding an area where the sun is in front of you and you are facing a wall. While watching the wall, raise the mirror until it catches the light. You will then need to focus the mirror by moving it back and forth until you see the sun in the mirror. It should look like a small point on the mirror. The distance between the mirror and the wall is the focal length. Measure the distance. The tube used for the telescope must be at least that of the focal length and the diameter of the tube should be at least the size of the concave mirror. The mirror is fitted into one end of the tube facing inward.
  
  

Reflecting Mirror

• From the mirror, mark on the tube 10 cm in from the end of the focal length. Take a smaller tube (small tube one) which will be used to build the ocular piece. Measure the diameter on the small tube one and where you made your mark on the large tube, cut a hole the same diameter as small tube one. This hole will eventually hold small tube one. From the hole you have cut, draw a line at a 90-degree angle down and repeat on the other side. Make two holes at the end of each 90-degree line. Insert a piece of thin, flat wood through the holes. Take a small flat mirror 1"x1" and attach double-sided tape to the back of mirror. Place the mirror through the ocular hole and attach to a dowel. Rotate the wood so the mirror is at a 45-degree angle with the diameter of the large tube. The flat mirror will reflect rays from the big, concave mirror.
  
  

The Occular Piece

• Take another small tube (small tube two) and cut along the length of the tube. Get a small magnifying glass and place the tube directly over it, wrapping the sides of the tube firmly over the magnifying glass. Tape the magnifying glass in place with duct tape. Insert the magnifying glass holder into small tube one. Small tube two should be able to slide in and out allowing you to focus on an object, but should also sit snugly in small tube one. Place the ocular piece into the ocular hole. Images which are collected by the concave mirror are reflected onto the flat mirror and then can be viewed through the ocular piece.