Telescope is an instrument designed for the observation of remote objects
and the collection of electromagnetic radiation. The earliest known telescopes are credited to
three individuals, Hans Lippershey and Zacharias Janssen, spectacle-makers in Middelburg, and
Jacob Metius of Alkmaar also known as Jacob Adriaanszoon (see History of telescopes).
"Telescope" (from the Greek tele = 'far' and skopein = 'to look or see';
teleskopos = 'far-seeing') was a name invented in 1611 by title="Prince Frederick Sesi">
Prince Frederick Sesi while watching a presentation of Galileo Galilei's instrument, which was
based on Hans Lippershey's design. "Telescope" usually refers to optical telescopes,
but there are telescopes that operate in other regions of the electromagnetic spectrum.
Binocular telescopes, or binoculars, (also known as field glasses)
are two identical or mirror symmetrical telescopes mounted side-by-side and aligned to
point accurately in the same direction, allowing the viewer to use both eyes binocular vision)
when viewing distant objects. Most are sized to be held using both hands, although there are much larger types.
Unlike a monocular telescope, binoculars give users a three-dimensional image: the two views,
presented from slightly different viewpoints to each of the viewer's eyes, merge to produce a
single perceived view with a sensation of depth, allowing distances to be estimated.
There is no need to close or obstruct one eye to avoid confusion, as is usual with monocular
telescopes. When using hand-held binoculars the two hands and the head form a steady three-point
platform, with less tendency to shake than a single-eye instrument.
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