 | |
| Type | Private |
|---|---|
| Industry | Manufacturing |
| Founded | 1950 |
| Headquarters | New Hope, Pennsylvania, United States |
Key people | Donald J. Bandurick, President and CEO |
| Products | Optical / mechanical devices |
| Website | www.questarcorporation.com |
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".
Questar was founded in 1950 by Lawrence Braymer, who set up Questar to develop and market Maksutov telescopes and other optical devices for the consumer, industrial, and government customers. The Questar Standard telescope has been in production since 1954.
Questars have been associated with many well-known scientists and other personalities; for example, in 1959, Wernher Von Braun purchased a telescope manufactured by the company. [1]
Questar produces telescopes for consumer, military, police, security, aerospace, and industrial applications. Products sold by Questar include 3.5” (89 mm) and 7” (178 mm) aperture Maksutov Cassegrain astronomical/terrestrial telescopes for the consumer market. For a while they also offered 12-inch (300 mm)-aperture optical-tube assemblies. They are used in astronomy, nature study, radar calibration/boresighting/tracking rocket launches, surveillance, and as long-distance microscopes.
Questar does not produce their own optics. The earliest Questars used optics produced in part by Cave Optical, but for most of their history the optics were produced by Cumberland Optical. [2]
In development since 1946, the Questar 3-1/2 has been the company's most notable product. Braymer’s basic concept for the telescope was one of portability, compactness, and ease of use. He used a catadioptric Maksutov design, named after its inventor Dmitry Maksutov, for the optical tube assembly. Braymer used a modified Cassegrain design that added an aluminized spot to the Maksutov corrector plate, creating a compact folded light path (this design is sometimes called a "Spot-Maksutov"). Braymer designed a built-in “Control Box” that allowed the user, looking through the main eyepiece, to switch between the main telescope and a coaxial finderscope via moving a diagonal out of the way with a flick of a knob. This also allowed a camera or other device to access the focal plane through a hole on the back of the Control Box. A knob for focus and another to switch in and out a magnification-doubling Barlow lens rounded out the controls. The cast-aluminum double-fork arm mount was designed with a built-in clock drive and became equatorial by adding the collapsible legs included. It also included a star chart engraved in white on a blue aluminum sleeve (this doubles as a dewcap), around the barrel which contained a moon map.
To avoid a conflict with a design patent held by John Gregory licensed to PerkinElmer, Braymer put the secondary spot on the outer (R1) surface of the corrector lens. In the mid-1960s the patent issue was settled, and Questar’s Maksutov-Cassegrains after that time use the Gregory design with the aluminized spot on the inside of the corrector (R2). [3] The design was originally envisioned as a 5-inch (130 mm) telescope, but it was decided a telescope of that size would not fit the market they were aiming for, since it would be too heavy and expensive. [4]
The Questar 3.5” entered commercial production in 1954 with ads for the model run in many astronomy, science, photography, and nature related magazines such as National Geographic , Scientific American and Sky & Telescope . The ads focused on the telescope's mechanical and optical design, educational value for children, ease of use, and adaptations as a spotting scope and telephoto lens. The Questar of the 1950s and early 1960s had a proprietary screw in eyepiece design and offered little capacity to employ third-party accessories. Later models accept standard slide-in 1.25" eyepieces and other accessories.
The Questar 3.5” has been sold in variants including: [5]
For use in the field of amateur astronomy where resolution and light-gathering power are the primary requirements for a telescope, the Questar 3-1/2's comparatively small aperture has led the instrument to be criticized by some as too small and too expensive. [6]
A 7-inch (180 mm) model was introduced in 1967 for amateur and professional astronomers, hobbyists, industry and government. A scaled-up version of the Questar 3.5" with the integrated Control Box, the Questar Seven, with a nominal 2400mm focal length, has twice the aperture and four times the light gathering power of the 3.5. The form-factor is similar to the 3.5 Duplex model as the barrel is separate but attaches to the base of the clock drive assembly. After over fifty years in production, the Seven remains rare. Using a sequential serial numbering system, approximately one thousand units have built since production began. The Seven was also very expensive for its intended market and has never been a big seller. [7]
The optical microscope, also referred to as a light microscope, is a type of microscope that commonly uses visible light and a system of lenses to generate magnified images of small objects. Optical microscopes are the oldest design of microscope and were possibly invented in their present compound form in the 17th century. Basic optical microscopes can be very simple, although many complex designs aim to improve resolution and sample contrast.
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.
In optical engineering, the objective is the optical element that gathers light from the object being observed and focuses the light rays to produce a real image. Objectives can be a single lens or mirror, or combinations of several optical elements. They are used in microscopes, binoculars, telescopes, cameras, slide projectors, CD players and many other optical instruments. Objectives are also called object lenses, object glasses, or objective glasses.
The Newtonian telescope, also called the Newtonian reflector or just a Newtonian, is a type of reflecting telescope invented by the English scientist Sir Isaac Newton, using a concave primary mirror and a flat diagonal secondary mirror. Newton's first reflecting telescope was completed in 1668 and is the earliest known functional reflecting telescope. The Newtonian telescope's simple design has made it very popular with amateur telescope makers.
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 the device. The objective lens or mirror collects light and brings it to focus creating an image. The eyepiece is placed near the focal point of the objective to magnify this image. 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.
Dmitry Dmitrievich Maksutov was a Russian / Soviet optical engineer and amateur astronomer. He is best known as the inventor of the Maksutov telescope.
A catadioptric optical system is one where refraction and reflection are combined in an optical system, usually via lenses (dioptrics) and curved mirrors (catoptrics). Catadioptric combinations are used in focusing systems such as searchlights, headlamps, early lighthouse focusing systems, optical telescopes, microscopes, and telephoto lenses. Other optical systems that use lenses and mirrors are also referred to as "catadioptric", such as surveillance catadioptric sensors.
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.
The Schmidt–Cassegrain is a catadioptric telescope that combines a Cassegrain reflector's optical path with a Schmidt corrector plate to make a compact astronomical instrument that uses simple spherical surfaces.
Celestron is an American 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.
Vixen is a Japanese company that makes telescopes, binoculars, spotting scopes and accessories for their products.
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.
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.
The ETX is a line of smaller aperture telescopes made by Meade Instruments.
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, was extended to the USA market.
A meniscus corrector is a negative meniscus lens that is used to correct spherical aberration in image-forming optical systems such as catadioptric telescopes. It works by having the equal but opposite spherical aberration of the objective it is designed to correct.
Astro-Physics, Inc. is a manufacturer of amateur telescopes, mounts, and accessories. Founded in 1975 by former Sundstrand Corporation engineer Roland Christen, the company is noted for its line of apochromatic refractors as well as high-end mounts. The company is located in Machesney Park, Illinois.
