"Seeing in the Dark"

There is no lens in this telescope. The light travels the length of the tube undisturbed to be reflected back to a focus near the top of the tube. The glass of the mirror need not be optical glass since its purpose is only to precisely support the aluminum reflecting coating. If you looked at the image with an eyepiece your head would block the incoming light. A small diagonal mirror is placed before the focus to reflect the light out the side of the tube for viewing. The telescope primary mirror must be polished very precisely to form the perfect image. It has been shown that persons of limited means are able to produce the precise mirror and the telescope. A telescope with a 12 inch primary mirror will gather about 2000 times more light than the unaided eye. Magnification is usually adjusted from 80X to more than 250X. A mid range of perhaps 140X is more usual unless atmospheric conditions are exceptional. Using our telescope faint objects such as planetary nebula, globular clusters and galaxies become visible. Faint gray appearing stars take on colors of blue, yellow or red. The polar cap of mars, the moons of Jupiter, and the rings of Saturn are easily seen. Viewing the moon as the earth�s rotation sweeps the field of view across the lunar craters reminds one of pictures taken from the Apollo Command Module while in orbit at the moon. If this type of thing interests you visit our links page.

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May 25, 2009