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were very popular in the second half of the 19th century, for most research purposes, the refracting telescope has been superseded by the reflecting telescope, which allows larger apertures.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.
An eyepiece, or ocular lens, is a type of lens that is attached to a variety of optical devices such as telescopes and microscopes. It is named because it is usually the lens that is closest to the eye when someone looks through an optical device to observe an object or sample. The objective lens or mirror collects light from an object or sample and brings it to focus creating an image of the object. The eyepiece is placed near the focal point of the objective to magnify this image to the eyes. The amount of magnification depends on the focal length of the eyepiece.
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 Soviet 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, LLC is a company 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.
Hisense Group is a Chinese multinational major appliance and electronics manufacturer headquartered in Qingdao, Shandong Province, China. Televisions are the main products of Hisense, and it is the largest TV manufacturer in China by market share since 2004. Hisense is also an OEM, so some of its products are sold to other companies and carry brand names not related to Hisense.
Grubb Parsons was a historic manufacturer of telescopes, active in the 19th and 20th centuries. They built numerous large research telescopes, including several that were the largest in the world of their type.
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. 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.
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. It markets telescopes and astronomy equipment, such as mounts and eyepieces, aimed at the amateur astronomy 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, Europe and in the late 2000s, it was extended to the United States 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.
The Porter Garden Telescope was an innovative ornamental telescope for the garden designed by Russell W. Porter and commercialized by Jones & Lamson Machine Company at the beginning of the 1920s in the United States.
