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These early telescopes were refracting telescopes. These telescopes used a lens as the objective. The objective is an optical element which gathers the light from the object that you are looking at. It is this refracted light that forms the image you see. This specific design was also used in the introduction of early spy glasses. It had been also used in telescopes designed for astronomy, and long-distance camera lenses. The down-side to this design is it has a physical size limit of about 40 inchesfor the objective, and then there was always a color distortion. There were some improvements in the design with the invention from the achromatic lens in 1733. Refracting telescopes stayed popular until the late 1800s.
Not long after the first refracting telescopes were designed, experimental testing was done using mirrors as a substitute for lenses. There were many attempted designs, but it was not until 1668 that Isaac Newton built the very first practical reflecting telescope. It had been aptly named the Newtonian reflector. Because of the size issue along with other limitations with the refracting design, most large research telescopes developed since the beginning of the 20th century have been of the reflecting variety. Without the dimensions restriction of refraction, one is able to make a reflecting telescope by having an objective size of over 10m. The reflector design wasn't without problems though, because the initial mirrors used in the designs would deteriorate quickly. These speculum mirrors, were produced from a mixture of copper and tin. Mixing both of these materials together with a small amount of arsenic correctly would produce a hard white alloy. When polished, this alloy would become highly reflective. These kinds of mirrors were used only before the introduction and advancement of silver coated glass mirrors in 1857, and aluminium mirrors in 1932. In the last 100 years there've also been telescopes designed that work in different wavelengths. The first radio telescope was developed in 1937, and there are also gamma ray telescopes in operation today.
Today, there's a large range of telescopes, all with different designs and benefits. You can even find Solar Telescopes, or Alpen Binoculars, designed specifically for viewing the sun. There are also scopes made specific for hunting, sports, birding and for the general outdoors. Spotting Scopes are extremely universal and may be used for a number of activities. For more information visit us at http://www.buytelescopes.com. We have a great selection of telescopes, including Kimber Rifle Scopes, Alpen Scopes and Meade Telescopes.
For more information about Takahashi Telescopes visit our website: Stellarvue
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