My father is a dentist and a long time ago he gave me a small dentist mirror. A few days ago I found this mirror again and I had an idea, to build the smallest Newtonian telescope in the world. I made some measurements on the mirror and I found it is 22 mm in diameter and a focal length of 81 mm. This gives a focal ratio of f/3.7, a very fast mirror. With some handycraft work I cut a PVC pipe of 32mm of diameter and 100 mm long. I made a small cell to support the mirror with screws, nuts and springs. I got a small eyepiece from a small microscope (a science collection I bought at a newspaper store). I cut a small (this word "small" is impossible to avoid) piece of a flat mirror and sanded it to get a ellipse shape for the secondary mirror (diagonal mirror) and glued it on the head of a screw.|
That's all I need, put all parts together and "viola" the smallest Newtonian telescope in the world. It has a blurry image but it magnifies about 8 times.
Length of the tube is 100 mm.
Diameter os tube is 32 mm.
The optic parts off the tube.
The small eyepiece to the left,
the main mirror on his cell at center
and the diagonal mirror at rigth.
Just compare with a mm/inchs tape.