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About Telescopes and Microscopes
For thousands of years mankind has sought ways of looking farther to see
distant objects, or looking closer to better see small objects.
Phoenicians cooking on sand discovered glass around 3500 BCE, but it
took about 5,000 years more for glass to be shaped into a lens for the first tele-
scope. A spectacle maker named Hans Lippershey (c1570-c1619) of Holland
looked at a church steeple through two lenses placed one in front of the other and
saw that the image was magnified. Lippershey is often credited with the invention of
the telescope, but he almost certainly was not the first to make one.
The telescope was introduced to astronomy in 1609 by the great Italian
scientist Galileo Galilei, who became the first man to see the craters of the moon,
and who went on to discover sunspots, the four large moons of Jupiter, and the
rings of Saturn. Galileo's telescope had limited magnification and a narrow field of
view. Galileo could see no more than a quarter of the moon's face without
repositioning his telescope.
Later, better telescopes using mirrors and various combinations of lenses
have been developed.
Refracting telescopes use
lenses to gather and bend light making
things seem larger. The lenses used in
refracting telescopes are called
concave and convex. Convex (curved
outward) lenses bend light inward,
making things bigger, but blurry.
Concave (curved inward) lenses bend
light outward, making things appear
small. A combination of these two
lenses can be used to adjust the
apparent size of objects, and make
them appear in focus.
This set contains lenses of different combinations of concave and convex
lenses. Some are individual lenses, and some are combinations of lenses
cemented together.
As you build and experiment with the various combinations of lenses,
think about how each one magnifies or reduces, bends or redirects light.
All lenses have an "Angle of View" which is a measure of the angle the
light is bent by the lens. This is also known as a "Focal Length" which is the
distance from the lens that the light bent by the lens comes back together in
focus. The Body, Drawtube, Eyepieces and Spacers included in this kit allow you
to adjust for the Focal Length of any combination of lenses.
SKU 93233
For technical questions please call 1-800-444-3353 Page 5
convex lens
concave lens
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