Binoculars or field glasses are two refracting telescopes mounted side-by-side and aligned to point in the same direction, allowing the viewer to use both eyes when viewing distant objects. Most binoculars are sized to be held using both hands, although sizes vary widely from opera glasses to large pedestal-mounted military models.
The history of the telescope can be traced to before the invention of the earliest known telescope, which appeared in 1608 in the Netherlands, when a patent was submitted by Hans Lippershey, an eyeglass maker. Although Lippershey did not receive his patent, news of the invention soon spread across Europe. The design of these early refracting telescopes consisted of a convex objective lens and a concave eyepiece. Galileo improved on this design the following year and applied it to astronomy. In 1611, Johannes Kepler described how a far more useful telescope could be made with a convex objective lens and a convex eyepiece lens. By 1655, astronomers such as Christiaan Huygens were building powerful but unwieldy Keplerian telescopes with compound eyepieces.
A refracting telescope is a type of optical telescope that uses a lens as its objective to form an image. The refracting telescope design was originally used in spyglasses and astronomical telescopes but is also used for long-focus camera lenses. Although large refracting telescopes were very popular in the second half of the 19th century, for most research purposes, the refracting telescope has been superseded by the reflecting telescope, which allows larger apertures. A refractor's magnification is calculated by dividing the focal length of the objective lens by that of the eyepiece.
An optical telescope is a telescope that gathers and focuses light mainly from the visible part of the electromagnetic spectrum, to create a magnified image for direct visual inspection, to make a photograph, or to collect data through electronic image sensors.
Pentax is a brand name used primarily by the Japanese multinational imaging and electronics company Ricoh for DSLR cameras, lenses, sport optics, and CCTV optics. The Pentax brand is also used by Hoya Corporation for medical products & services, TI Asahi for surveying instruments, and Seiko Optical Products for certain optical lenses.
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.
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.
Tele Vue Optics is a Chester, New York-based astronomical optics company known primarily for its premium brand of speciality eyepieces and apochromatic refractor telescopes. Founded in 1977 by Al Nagler, an optical engineer from The Bronx who designed simulators used in the Apollo program, the company originally made projection lenses for large projection-screen televisions, but is well known in the astronomy community for its products.
Custer Observatory is an astronomical observatory owned and operated by Custer Institute. Located in Southold, New York (US), facing Peconic Bay and Shelter Island, Custer's location boasts some of the darkest skies on Long Island.
Hisense Group is a Chinese multinational white goods and electronics manufacturer headquartered in Qingdao, Shandong Province, China. It started out making radios in 1969.
Questar Corporation is a company based in New Hope, Pennsylvania. It manufactures precision optical devices for consumer, industrial, aerospace, and military markets. Its telescopes produced for the consumer market are sold under the brand name "Questar".
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.
The following timeline lists the significant events in the invention and development of the telescope.
Inventec Corporation is a Taiwan-based Original Design Manufacturer (ODM) making notebook computers, servers and mobile devices. Originally established in 1975 to develop and manufacture electronic calculators, major customers include Hewlett-Packard, Toshiba, Acer, and Fujitsu-Siemens.
Tasco sells consumer telescopes. Tasco mainly imports telescopes for amateur astronomers but has expanded into other optical products, such as spotting scopes, microscopes, binoculars, telescopic sights, and other rifle accessories. Tasco sells via retail stores, catalogs, and online retailers. Tasco is based in Miramar, Florida. George Rosenfield founded the firm as the Tanross Supply Company in 1954. It started as a distributor of fishing tackle and hardware. The name was later shortened to Tasco as its offerings expanded to include binoculars and eyepieces.
Sky-Watcher is a commercial distribution company established in 1999 by the Synta Technology Corporation of Taiwan that markets telescopes and astronomical equipment, like mounts and eyepieces, aimed at the amateur astronomical market. The products are manufactured at Synta Taiwan's Suzhou Synta Optical Technology Co., Ltd. in Suzhou (Jiangsu), China. The brand is distributed in Canada and Europe and, in the late 2000s, extended to the USA market.
Takahashi Seisakusho Ltd. (株式会社高橋製作所) is a Japanese manufacturer of telescopes and related equipment founded in 1932 by Kitaro Takahashi in Tokyo. Originally started as a foundry, Takahashi began manufacturing optical equipment after WWII in 1946.
Explore Scientific is a company founded by former Meade Instruments Vice President of Brand Community Scott W. Roberts in 2008. Headquartered in Springdale, Arkansas, the company designs and manufactures telescopes, spotting scopes, binoculars, microscopes and other scientific devices. Products are manufactured in China by JOC and imported. For Europe the Explore Scientific GmbH is responsible for the distribution of these products.
Synta Technology Corporation of Taiwan, also known as Synta, is a manufacturer of telescopes and optical components headquartered in Taoyuan, Taiwan.
