|
|
The telescope
is an instrument designed to magnify and observe distant objects. German-Dutch lens maker, Hans Lippershey, is credited with inventing the first functioning telescope in 1608. The name, “telescope,” is from the Greek words for “far” and “to look or see,” and was first given to Galileo Galilei’s instrument used for viewing distant objects. “Telescope” can actually refer to a wide range of instruments operating in most regions of the electromagnetic spectrum, but the most common type is the optical telescope. An optical telescope increases the apparent size of an object, as well as the apparent brightness. It works by gathering and focusing light mainly from the visible part of the electromagnetic spectrum (although some telescopes work in the infrared and ultraviolet spectrum). It uses one or more curved optical elements - usually made from glass lenses or mirrors to gather light or other electromagnetic radiation and bring that light or radiation to a focus, so that the image can then be observed, studied, photographed or sent to a computer. Optical telescopes are used for astronomy and in many non-astronomical instruments, including: binoculars, spotting scopes, theodolites (including transits), monoculars, camera lenses, and spy glasses.
There are three main types of telescopes:
The refracting telescope, which solely uses an arrangement of glass lenses (excluding star diagonals).
The reflecting telescope, which uses solely an arrangement of mirrors (excluding eyepieces).
The catadioptric telescope, which uses a combination of mirrors and lenses, and usually have a glass corrector plate at the front.
Most telescopes are either refracting or reflecting. Both basically accomplish the same thing, but in different ways. Telescopes come in many different shapes, sizes and prices, from a “toy” that may cost $5.00 to the Hubble Space Telescope that weighs several tons. Of course, most amateur telescopes fall somewhere in-between. Also, remember when viewing the night skies, you wont see Hubble-quality images, but it will be fascinating, just the same. Amateur telescope making is becoming quite popular and is considered an offshoot of amateur astronomy. Amateur telescope makers (called “ATMs”) are not paid professionals but build telescopes as a hobby, or to make a personal contribution to the field of astronomy.
Tips for purchasing a telescope:
Aperture is a more important feature than magnification, so don’t base your purchase on a claim for “high power magnification.” In fact, most astronomical objects are best viewed with lower magnification to gather the most light possible. You want to purchase as much aperture as you can afford, but take other factors into consideration, as well.
Consider weight, size and storage. Large telescopes are heavy to carry around and take up a lot storage space.
Check the focuser on the telescope to make sure it moves smoothly without causing your telescope to shake.
Check for eye pieces. Some telescopes come with an eyepiece - others come with none. If you purchase a separate one, make sure it fits your telescope.
Your telescope needs to be stable, so look for a steady mount that adequately supports your telescope.
Find a telescope to fit your budget. Models range from a couple of hundred dollars to several thousands of dollars.
|
|
|
