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An optical telescope gathers and focuses light mainly from the visible part of the electromagnetic spectrum (although
some work in the infrared and ultraviolet). Optical telescopes increase the apparent angular size of distant objects as well as their
apparent brightness. In order for the image to be
observed, photographed and studied, telescopes work
by employing one or more curved optical elements—usually made from glass—lenses, or mirrors to gather light to bring that light or radiation to a focal point. Optical
telescopes are used for astronomy and in many non-astronomical
instruments, including: spotting scopes, monoculars and
binoculars.
Refracting Telescopes
Pros:
- Great for moon, planets, and stars
- Require almost no maintenance
- Classic telescope design
Cons:
- Most expensive per inch of aperture
- Less suited for faint, deep-sky objects
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Reflecting Telescopes
Pros:
- Least expensive per inch of aperture
- Large apertures for deep-sky viewing
- Reasonably compact and portable
- Delivers very bright images
Cons:
- Not too well suited for terrestrial viewing
- Slight light loss due to mirror system
- May need simple mirror alignment
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Catadioptric Telescopes
Pros:
- Easy to use, compact and portable
- Excellent optics provide sharp images
- Great for astrophotography
- Best telescope design
Cons:
- Expensive
- Unusual appearance
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