Tom Johnson (astronomer)

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Thomas Jasper Johnson or Tom Johnson (January 11, 1923 – March 13, 2012) [1] was an American electronics engineer and astronomer who founded Celestron, a company which manufacturers telescopes, which revolutionized the amateur astronomy industry and hobby. [2] [3] Sky & Telescope magazine has called him, "among the most important figures shaping the last half century of amateur astronomy." [3]

Johnson was born in 1923. [3] He served as a military radar technician during World War II. [3]

In 1955, Johnson, an engineer, established Valor Electronics, which produced electronics for military and industrial use. [2] [3] Valor, which was headquartered in Gardena, California, had more than one hundred employees by the early 1960s. [3]

Johnson, who had a strong interest in amateur astronomy, originally created Celestron as the "Astro-Optical" division of Valor Electronics in 1960. [2] [3] Around 1960, Johnson had been looking for a telescope which could be used by his two sons, but found no such child-friendly models on the market at the time. [2] Johnson built a new telescope, a 6-inch reflector telescope, by himself, in 1960. [2] He was visiting his brother in Costa Mesa, California when he came upon his nephew, Roger, trying to grind the 6 inch diameter lens he purchased from the clearance table at a local hobby shop. Roger was tired of the project and offered the lens-grinding kit to his uncle. Thomas Jasper took the kit home and after several days of hand grinding, he invented a machine that would grind the lens for him. Thus, by accepting the lens grinding kit from his nephew, Roger L. Johnson, "TJ" (as the family called him) created that first lens of many.

On July 28, 1962, he publicly unveiled a new invention, a portable 18+34-inch Cassegrain telescope, at the party held by the Los Angeles Astronomical Society on Mount Pinos. [3] The new transportable telescope proved so groundbreaking that Johnson's invention was featured on the cover of a 1963 issue of Sky & Telescope . [3]

Johnson's interest in telescopes soon became a full-fledged business. [2] Johnson's new company, Celestron, which descended from the "Astro-Optical" division of Valor Electronics, soon began selling more sophisticated Schmidt–Cassegrain telescopes in models ranging from just 4 inches to 22 inches. [2] However, the Schmidt–Cassegrain telescope proved difficult to mass-produce because the models needed Schmidt corrector plate, an advanced aspheric lens, which could be hard to manufacture. [2] To solve this production problem, Johnson and the company's engineers invented a new type of telescope, the Celestron 8, in 1970. [2] The Celestron 8 was more compact, affordable and easier to manufacture than traditional telescopes, like the Schmidt–Cassegrain. [2] Johnson's new telescope proved very popular in the amateur astronomy and educational industries, allowing the hobby to rapidly expand and reach more consumers. [2]

Johnson sold Celestron in 1980. [2]

Johnson was awarded the David Richardson Medal from the Optical Society of America in 1978, the Bruce Blair Medal from the Western Amateur Astronomers in 1993, and the Lifetime Achievement Award by the Small Telescope & Astronomical Society in 2009. [2] [3]

Tom Johnson died at 5 a.m. PST on March 13, 2012, at the age of 89. [2]

Related Research Articles

Amateur telescope making

Amateur telescope making is the activity of building telescopes as a hobby, as opposed to being a paid professional. Amateur telescope makers build their instruments for personal enjoyment of a technical challenge, as a way to obtain an inexpensive or personally customized telescope, or as a research tool in the field of astronomy. Amateur telescope makers are usually a sub-group in the field of amateur astronomy.

Astrophotography Astronomical imaging

Astrophotography, also known as astronomical imaging, is the photography or imaging of astronomical objects, celestial events, or areas of the night sky. The first photograph of an astronomical object was taken in 1840, but it was not until the late 19th century that advances in technology allowed for detailed stellar photography. Besides being able to record the details of extended objects such as the Moon, Sun, and planets, modern astrophotography has the ability to image objects invisible to the human eye such as dim stars, nebulae, and galaxies. This is done by long time exposure since both film and digital cameras can accumulate and sum photons over these long periods of time.

Schmidt corrector plate Corrective lens used in Schmidt and Schmidt–Cassegrain telescopes

A Schmidt corrector plate is an aspheric lens which corrects the spherical aberration introduced by the spherical primary mirror of the Schmidt or Schmidt–Cassegrain telescope designs. It was invented by Bernhard Schmidt in 1931, although it may have been independently invented by Finnish astronomer Yrjö Väisälä in 1924. Schmidt originally introduced it as part of a wide-field photographic catadioptric telescope, the Schmidt camera. It is now used in several other telescope designs, camera lenses and image projection systems that utilise a spherical primary mirror.

Schmidt camera Astrophotographic telescope

A Schmidt camera, also referred to as the Schmidt telescope, is a catadioptric astrophotographic telescope designed to provide wide fields of view with limited aberrations. The design was invented by Bernhard Schmidt in 1930.

The Meade Instruments is an American multinational company headquartered in Watsonville, California, that manufactures, imports, and distributes telescopes, binoculars, spotting scopes, microscopes, CCD cameras, and telescope accessories for the consumer market. It is the world's largest manufacturer of telescopes.

Siding Spring Observatory Astronomic observatory in New South Wales, Australia

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Catadioptric system Optical system where refraction and reflection are combined

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Maksutov telescope

The Maksutov is a catadioptric telescope design that combines a spherical mirror with a weakly negative meniscus lens in a design that takes advantage of all the surfaces being nearly "spherically symmetrical". The negative lens is usually full diameter and placed at the entrance pupil of the telescope. The design corrects the problems of off-axis aberrations such as coma found in reflecting telescopes while also correcting chromatic aberration. It was patented in 1941 by Russian optician Dmitri Dmitrievich Maksutov. Maksutov based his design on the idea behind the Schmidt camera of using the spherical errors of a negative lens to correct the opposite errors in a spherical primary mirror. The design is most commonly seen in a Cassegrain variation, with an integrated secondary, that can use all-spherical elements, thereby simplifying fabrication. Maksutov telescopes have been sold on the amateur market since the 1950s.

Celestron is a company based in Torrance, California, United States, that manufactures telescopes and distributes telescopes, binoculars, spotting scopes, microscopes, and accessories manufactured by its parent company, the Synta Technology Corporation of Taiwan.

Cassegrain reflector Combination of concave and convex mirrors

The Cassegrain reflector is a combination of a primary concave mirror and a secondary convex mirror, often used in optical telescopes and radio antennas, the main characteristic being that the optical path folds back onto itself, relative to the optical system's primary mirror entrance aperture. This design puts the focal point at a convenient location behind the primary mirror and the convex secondary adds a telephoto effect creating a much longer focal length in a mechanically short system.

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UNA Observatory is an astronomical observatory owned and operated by the University of North Alabama. It is located in Florence, Alabama (USA). It has 2 telescopes, a Celestron 0.35 m Schmidt–Cassegrain telescope. The UNA Planetarium is a 65-seat planetarium with a Spitz A3P projector and East Cost Control Systems controller.

Custer Observatory Observatory

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Orion Telescopes & Binoculars is an American retail company that sells telescopes, binoculars and accessories online and in-store for astronomy and birdwatching. It was founded in 1975 and has corporate offices in Watsonville, California with a retail store in Cupertino, California. A large proportion of its products are manufactured by the Chinese company Synta for the Orion brand name. Orion Telescopes & Binoculars ships its products to the United States and over 20 other countries. Orion puts out a semi-quarterly mail-order catalog as well as email catalogs. The company is a prominent advertiser in North American astronomy magazines, such as Sky & Telescope and Astronomy.

Hoober Observatory Observatory

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The SUNY Oneonta College Observatory is an astronomical observatory in Oneonta, New York. The observatory is home to the largest optical telescope in New York: a 1-meter Newtonian reflector. It is also believed to be the one of the largest telescopes open for public observing east of the Mississippi. The telescope was constructed by JMI Telescopes of Lakewood, Colorado.

The Whakatane Astronomical Society is a voluntary, non-profit society for people interested in amateur astronomy in the Whakatane District of New Zealand. The society was founded in September 1960, and maintains a small observatory in Whakatane, which has been operating continuously since 1964. The society is affiliated with the Royal Astronomical Society of New Zealand.

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References

  1. "Celestron founder dies at age 89". Astronomy . Retrieved 2014-01-27.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Ferron, Karri (2012-03-13). "Celestron founder dies at age 89, Tom Johnson founded the telescope company in 1960 and revolutionized the hobby with the Celestron 8". Astronomy Magazine . Retrieved 2012-03-28.
  3. 1 2 3 4 5 6 7 8 9 10 di Cicco, Dennis (2012-03-13). "Tom Johnson, 1923–2012". Sky & Telescope . Retrieved 2012-03-28.