While there are countless variations, (both mirrors spherical, both mirrors aspherical, or one of each) they can be divided into two principal design forms: compact and non-compact. In the compact form, the corrector plate is located at or near the focus of the primary mirror. In the non-compact, the corrector plate remains at or near the center of curvature (twice the focal length) of the primary mirror. Typical examples of the compact design are Celestron and Meade commercial instruments, combining a fast primary mirror and a small, strong ...

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Schmidt-Cassegrain telescope, Schmidt-Cassegrain telescope - Variations, Schmidt-Cassegrain telescope - Notable telescopes

Read more here: » Schmidt-Cassegrain telescope: Encyclopedia II - Schmidt-Cassegrain telescope - Variations

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Refracting telescope, Refracting telescope - Technical difficulties, Refracting telescope - Notable refracting telescopes

Read more here: » Refracting telescope: Encyclopedia II - Refracting telescope - Notable refracting telescopes

Refractors are criticized for their relatively high-degree of residual chromatic and spherical aberration. This affects shorter focal lengths more than longer ones. A 4" F6 achromatic refractor is likely to show considerable color fringing. (generally a purple halo around bright objects) A 4" F16 will have little color fringing. In very large apertures, there is also a problem of lens sagging, a result of gravity deforming glass. There is a further problem of glass defects, striae or small air bubbles trapped within the glass. In addi ...

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Refracting telescope, Refracting telescope - Technical difficulties, Refracting telescope - Notable refracting telescopes

Read more here: » Refracting telescope: Encyclopedia II - Refracting telescope - Technical difficulties

A telescope (from the Greek tele = 'far' and skopein = 'to look or see'; teleskopos = 'far-seeing') is an optical tool which gathers and focuses electromagnetic radiation. Telescopes increase the apparent angular size of distant objects, as well as their apparent brightness. Telescopes are used for astronomy and in many non-astronomical instruments including theodolites, transits, spotting scopes, monoculars, binoculars, camera lenses and spyglasses. The word "telescope" usually refers to optical telescopes, but there are telescopes for mo ...

Including:

• Telescope - History
• Telescope - Types
• Telescope - Telescope mountings
• Telescope - Research telescopes
• Telescope - Imperfect images
• Telescope - The five Seidel aberrations
• Telescope - The chromatic aberrations
• Telescope - Famous optical telescopes
• Telescope - Related lists

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There is a strong tradition of amateur telescope making within the amateur astronomy community. The classic amateur telescope is the Newtonian reflector with a dobsonian type mount, also known as a "Dobsonian telescope." Some also build refractors and a very few attempt compound designs such as the Maksutov telescope. Amateur telescope makers typically make the most critical parts of ...

Including:

• Amateur telescope making - Telescope design
• Amateur telescope making - Mirror making
• Amateur telescope making - Grinding
• Amateur telescope making - Polishing
• Amateur telescope making - Mirror testing
• Amateur telescope making - Figuring the mirror
• Amateur telescope making - Aluminizing or silvering the mirror
• Amateur telescope making - Telescope construction
• Amateur telescope making - Tube
• Amateur telescope making - Mount
• Amateur telescope making - Telescope making books and other published information

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Meade is a company that produces telescopes, binoculars, spotting scopes, microscopes, CCD cameras and accessories for their products. Their most popular line of telescopes include the LX200 series of "GO-TO" ranging from eight to sixteen inch diameter Schmidt-Cassegrain telescopes, the modified Ritchey-Chrétien RCX400 series 10 to 16-inch diameter introduced in 2005, as well as smaller Maksutov-Cassegrain telescopes. Others include the RDX "GO-TO" German equatorial mount series, with telescopes ranging from a 6-inch refractor and re ...

Including:

• Meade - External link

Read more here: » Meade: Encyclopedia - Meade

First developed in 1672 by Laurent Cassegrain, a Cassegrain Telescope this type of reflector is a combination of a prime concave and a secondary convex mirror, both aligned axially. The prime mirror usually contains a hole in the centre thus permitting the light to reach an eyepiece, a camera, or a light detector. Concave Mirror: Paraboloid type Convex Mirror: Hyperboloid type A Cassegrain reflecting telescope consists of primary and secondary reflecting mirrors. In a traditional Newtonian reflector ...

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Celestron is a company that makes telescopes, binoculars, spotting scopes, microscopes, and accessories for their products. The company was US owned until April 2005 when it was acquired by SW Technology Corporation, a Delaware company and affiliate of Synta Technology Corporation in China. Synta is a leading manufacturer of astronomy equipment that are copies of original designs by companies such as Celestron and Vixen. Celestron had struggled to remain profitable in an aggressive but limited market, in particular follo ...

Read more here: » Celestron: Encyclopedia - Celestron

Amateur astronomy, often called back yard astronomy, is a hobby whose participants enjoy observing celestial objects. It is usually associated with viewing the night sky when most celestial objects and events are visible, but sometimes amateur astronomers also operate during the day for events such as sunspots and solar eclipses. Amateur astronomers often look at the sky using nothing more than their eyes, but common tools for amateur astronomy include portable telescopes and binoculars. Amateur astronomy - ...

Including:

• Amateur astronomy - Amateur astronomy and scientific research
• Amateur astronomy - Societies for amateur astronomy
• Amateur astronomy - Approaches to using amateur telescopes
• Amateur astronomy - Star hopping
• Amateur astronomy - GOTO telescopes
• Amateur astronomy - Comparing methodologies
• Amateur astronomy - Additional tools and activities
• Amateur astronomy - Beginning in amateur astronomy
• Amateur astronomy - Beginning with a GOTO telescope
• Amateur astronomy - Becoming acquainted with the night sky
• Amateur astronomy - Suggested reading

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Astronomy (Greek: αστρονομία = άστρον + νόμος, astronomia = astron + nomos, literally, "law of the stars") is the science of celestial objects and phenomena that originate outside the Earth's atmosphere, such as stars, planets, comets, galaxies, and the cosmic background radiation. It is concerned with the formation and development of the universe, the evolution and physical and chemical properties of celestial objects and the calculation of their motions. Astronomical observations are ...

Including:

• Astronomy - Divisions
• Astronomy - By subject or problem addressed
• Astronomy - Ways of obtaining information
• Astronomy - History of astronomy
• Astronomy - Timelines in astronomy
• Astronomy - Astronomy tools

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Refractors are criticized for their relatively high-degree of residual chromatic and spherical aberration. In very large apertures, there is also a problem of lens sagging, a result of gravity deforming glass. There is a further problem of glass defects, striae or small air bubbles trapped within the glass. In addition, glass is opaque to certain wavelengths, and even visible light is dimmed by reflection and absorption when it crosses the air-glass interfaces and passes through the glass itself. Most -or all- these problems are avoided by using r ...

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Refracting telescope, Refracting telescope - Technical difficulties, Refracting telescope - Notable refracting telescopes

Read more here: » Refracting telescope: Encyclopedia II - Refracting telescope - Technical difficulties

Telescopes are broadly classified into two main types. Optical telescopes Radio telescopes Optical telescopes are also divided into two types. Galilean refracting telescopes Newtonian reflecting telescopes Galilean or refracting telescopes employ the refractive properties of light, and are constructed of lenses. These can be used for both terrestrial and astronomical viewing. Newtonian or reflecting telescopes employ the reflect ...

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Telescope, Telescope - History, Telescope - Types, Telescope - Telescope mountings, Telescope - Research telescopes, Telescope - Imperfect images, Telescope - The five Seidel aberrations, Telescope - The chromatic aberrations, Telescope - Famous optical telescopes, Telescope - Related lists

Read more here: » Telescope: Encyclopedia II - Telescope - Types

The telescopes are broadly classified into two main categories. Optical telescopes Radio telescopes The optical telescopes are again divided into two Galilean refracting telescopes Newtonian reflecting telescopes The Galilean or refracting telescopes used refraction property of light. They were made up of lenses. They can be used for both terrestrial as well as astronomical viewing. The Newtonian or reflecting telescopes used reflec ...

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Telescope, Telescope - History, Telescope - Types, Telescope - Telescope mountings, Telescope - Research telescopes, Telescope - Imperfect images, Telescope - The five Seidel aberrations, Telescope - The chromatic aberrations, Telescope - Famous optical telescopes, Telescope - Related lists

Read more here: » Telescope: Encyclopedia II - Telescope - Types

The first telescopes may have been Assyrian crystal lenses. Article The Visby lenses tentatively suggest that the technology was known to the Arabs and Persians then to the Vikings in the 10th century. Leonard Digges is sometimes credited with the invention in England in the 1570s, but usually credit for assembling the first telescope is usually given to an unknown Dutch spectacle maker in about 1608. Some name that person as Hans Lippershey (c1570-c1619), but Jacob Metius and Zacharias Jansen also claimed to have invented a telescope ...

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Telescope, Telescope - History, Telescope - Types, Telescope - Telescope mountings, Telescope - Research telescopes, Telescope - Imperfect images, Telescope - The five Seidel aberrations, Telescope - The chromatic aberrations, Telescope - Famous optical telescopes, Telescope - Related lists

Read more here: » Telescope: Encyclopedia II - Telescope - History

The first telescopes may have been Assyrian crystal lenses. Article Though the Visby lenses tentatively suggest that the technology was known to the Arabs and then to the Vikings in the 10th century, credit for assembling the first telescope is usually given to an unknown Dutch spectacle maker in about 1608. Some name that person as Hans Lippershey (c1570-c1619). Even if Lippershey did not make the first one, he publicized it. Galileo Galilei made his own telescope in 1609, calling it at first a perspicillum, and then using the ...

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Telescope, Telescope - History, Telescope - Types, Telescope - Telescope mountings, Telescope - Research telescopes, Telescope - Imperfect images, Telescope - The five Seidel aberrations, Telescope - The chromatic aberrations, Telescope - Famous optical telescopes, Telescope - Related lists

Read more here: » Telescope: Encyclopedia II - Telescope - History

A simple telescope mount is an altitude-azimuth or altazimuth mount. It is similar to that of a surveying transit. A fork rotates in azimuth (in the horizontal plane), and bearings on the tips of the fork allow the telescope to vary in altitude (in a vertical plane). A Dobsonian mount is a type of altazimuth mount which has proven to be very popular as it is simple and inexpensive. When using an altazimuth for astronomy, both axes must be continuously adjusted to compensate for the Earth's rotation. Even if this i ...

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Telescope, Telescope - History, Telescope - Types, Telescope - Telescope mountings, Telescope - Research telescopes, Telescope - Imperfect images, Telescope - The five Seidel aberrations, Telescope - The chromatic aberrations, Telescope - Famous optical telescopes, Telescope - Related lists

Read more here: » Telescope: Encyclopedia II - Telescope - Telescope mountings

A simple telescope mount is an altitude-azimuth or altazimuth mount. It is similar to that of a surveying transit. A fork rotates in azimuth (in the horizontal plane), and bearings on the tips of the fork allow the telescope to vary in altitude (in a vertical plane). A dobsonian mount is a type of altazimuth mount which has proven to be very popular as it is simple and cheap to make. The major problem with using an altazimuth for astronomy is that both axes must be continuously adjusted to compensate for the Earth ...

See also:

Telescope, Telescope - History, Telescope - Types, Telescope - Telescope mountings, Telescope - Research telescopes, Telescope - Imperfect images, Telescope - The five Seidel aberrations, Telescope - The chromatic aberrations, Telescope - Famous optical telescopes, Telescope - Related lists

Read more here: » Telescope: Encyclopedia II - Telescope - Telescope mountings

Most large research telescopes can operate as either a Cassegrain telescope (longer focal length, and a narrower field with higher magnification) or a Newtonian telescope (brighter field). They have a pierced primary mirror, a Newtonian focus, and a spider to mount a variety of replaceable secondary mirrors. A new era of telescope making was inaugurated by the Multiple Mirror Telescope (MMT), with a mirror composed of six segments synthesizing a mirror of 4.5 meters diameter. This has now been replaced by a single 6.5m mirror. Its example was followed by ...

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Telescope, Telescope - History, Telescope - Types, Telescope - Telescope mountings, Telescope - Research telescopes, Telescope - Imperfect images, Telescope - The five Seidel aberrations, Telescope - The chromatic aberrations, Telescope - Famous optical telescopes, Telescope - Related lists

Read more here: » Telescope: Encyclopedia II - Telescope - Research telescopes

Most large research telescopes can operate as either a cassegrain telescope (longer focal length, and a narrower field with higher magnification) or newtonian telescope (brighter field). They have a pierced primary, a newtonian focus, and a spider to mount a variety of replaceable secondaries. A new era of telescope making was inaugurated by the MMT, with a mirror composed of six segments synthesizing a mirror of 4.5 metres diameter (this has now been replaced by a single 6.5m mirror). Its example was followed by ...

See also:

Telescope, Telescope - History, Telescope - Types, Telescope - Telescope mountings, Telescope - Research telescopes, Telescope - Imperfect images, Telescope - The five Seidel aberrations, Telescope - The chromatic aberrations, Telescope - Famous optical telescopes, Telescope - Related lists

Read more here: » Telescope: Encyclopedia II - Telescope - Research telescopes

No telescope can form a perfect image. Even if a reflecting telescope could have a perfect mirror, or a refracting telescope could have a perfect lens, the effects of aperture diffraction could still not be escaped. In reality, perfect mirrors and perfect lenses do not exist, so image aberrations in addition to aperture diffraction must be taken into account. Image aberrations can be broken down into two main classes, monochromatic, and polychromatic. In 1857, Philipp Ludwig von Seidel (1821-1896) decomposed the first order monochromatic aberrations into five constituent aberrations. They are now common ...

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Telescope, Telescope - History, Telescope - Types, Telescope - Telescope mountings, Telescope - Research telescopes, Telescope - Imperfect images, Telescope - The five Seidel aberrations, Telescope - The chromatic aberrations, Telescope - Famous optical telescopes, Telescope - Related lists

Read more here: » Telescope: Encyclopedia II - Telescope - Imperfect images