PURPOSE: To illustratre how an astronomical telescope can aid the eye.
DESCRIPTION: The TV camera functions as the eye, so what the eye sees can
be viewed on a monitor or the rear
projection screen. A 5 cm convex lens acts as the eyepiece and a 20 cm convex lens is the
objective lens, with the TV
camera focused at infinity (relaxed eye). The rule is positioned across the lecture hall
(at infinity) from the telescope.
The image is seen to be inverted and to have a magnification. The magnification can be
checked by viewing a two-meter stick with the TV camera directly and then with the
telescope.
To set up in practice, set the camera focus and lens positions and move the objective lens
until the image is seen by the
camera.
EQUIPMENT: Camera, lenses, optical rail.
Updated by Jun Qi in 3/22/2000