||This article contains content that is written like an advertisement. (July 2008)|
|Headquarters||New Hope, Pennsylvania, USA|
|Donald J. Bandurick, President and CEO|
|Products||Optical / mechanical devices|
Questar Corporation is a company based in New Hope, Pennsylvania, which manufactures precision optical devices for consumer, industrial, aerospace, and military markets. Its telescopes produced for the consumer market are sold under the name brand name "Questar".
Origins and history
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 probably making it the longest running production consumer oriented telescope.
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. The optics are hand-aspherized.
Questars have been associated with many well-known scientists and other personalities; Wernher Von Braun purchased one in 1959. Talk show host Johnny Carson, well known as a fan of astronomy, purchased an early model. Today Show founding host Dave Garroway, actor Marlon Brando, Arizona Senator Barry Goldwater, and Arthur C. Clarke were other well-known owners.
Questar's telescopes are used in consumer, military, police, security, and industrial applications. Products sold by Questar include 3.5” and 7” aperture Maksutov Cassegrain astronomical/terrestrial telescopes for the consumer market.
Other products included:
- Surveillance versions of their Maksutov-Cassegrain models
- Long-distance microscopes (e.g. QM-1), an adaptation of their Maksutov-Cassegrain telescopes modified to image subjects at close range, used in research and manufacturing process quality control
- Specially built Maksutov-Cassegrains for use in test range imaging and radar calibration/boresighting
- The QMax, a portable solar spectrometer built to fit their line of Maksutov-Cassegrain telescopes.
While it was produced in very limited numbers, Questar once offered a 12-inch (300 mm)-aperture optical-tube assembly. Some barrels were sold coupled with an equatorial mount based on a Byers drive system. The 12" Questar also found application by NASA for tracking launches optically (see below).
The Questar 3-1/2” Maksutov Cassegrain
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). To avoid a conflict with a design patent held by John Gregory licensed to Perkin-Elmer, 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). 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.
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.
The Questar 3.5” entered commercial production in 1954, and almost immediately this “observatory-in-a-box“ was considered the "Rolls-Royce" of telescopes. Ads for the model have run in many astronomy, science, photography, and nature related magazines such as National Geographic, Scientific American and Sky & Telescope. They have focused on the telescope's mechanical and optical quality, educational value for children, ease of use, and adaptations as a spotting scope and telephoto lens. The Questar of the 1950s and early 1960s offered little capacity to employ third-party accessories, although there was a range of accessories made by Questar itself. Later models have the added advantage of accepting standard 1.25" eyepieces and other accessories.
The Questar 3.5” has been available in 5 major variants:
- A 3.5" integrated telescope (referred to as a Questar Standard) with a star chart engraved in white on a blue aluminum sleeve (this doubles as a dewcap), around the barrel which contains a moon map.
- A 3.5" Field Model Questar, which is just the optical tube. See duplex option below. This was first offered for sale in May 1956.
- A 3.5" Duplex, optically and mechanically identical to the Standard, but which included a simple way of detaching the telescope from the open fork mount to allow the optical tube assembly (ota) to be used as a 1240 mm at f12 telephoto lens. This variant has been in production since 1967.
- A 3.5" convertible model that came with two barrels: the standard one, and a separate longer barrel, which could be screwed onto the duplex fork mount in place of the standard one, and used as a distance microscope. This variant came with the standard accessories, and a separate case containing the distance microscope barrel assembly.
- A 3.5" Questar Birder. This is a modified Questar Field Model with a fixed 10x finder with a rapid-focus knob used for observing birds and other wildlife.
A 7-inch (180 mm) model was introduced in 1967 for hobbyist, industry and government. It appears as a scaled-up Questar 3-1/2" with the integrated Control Box. But because of its high cost compared with similar-aperture consumer telescopes, the Seven has never been a big seller among the amateur market.
Versions of the Questar 3-1/2" were used by NASA during its early years. The first telescopic images of earth taken by astronauts in space were with a Questar 3-1/2" from a Gemini spacecraft. The Apollo astronauts used Questars on their missions to the moon as well. For camera tracking of launches, NASA still uses 12-inch (300 mm) Questar telescopes mounted on an anti-aircraft gun mount.
Since the telescope is made in a small production run by a relatively small company, the economies of scale have meant that the Questar 3-1/2” comes with a high price tag. Also, the basic design has remained almost static since its first production. 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 as too small and too expensive, especially in a market where instruments more than twice its aperture are available at half its price.
- J.R. Cumberland, Inc - Questar
- Kennedy Space Center's Amateur Astronomers' "A TELESCOPE FROM HISTORY OWNED BY DR. WERNHER von BRAUN"
- TelescopeOptics.net, 10.2.3.3. Maksutov-Cassegrain telescope "Questar Maksutov-Cassegrain, a design very similar to Gregory's (in order to avoid patent infringement, Questars had - for about a decade - the aluminized spot placed at the front meniscus surface)"
- Paul Yates, THE QUESTAR, COSMOS - HEBDEN BRIDGE ASTRONOMY SOCIETY, page 7, September 2000
- Rod Mollise, "Choosing and Using a New CAT", page 96
- Joe Bergeron's Astronomy Equipment Reviews - Questar 3.5"
- Sky & Telescope Magazine - November 2002, S&T Test Report : The Questar 50th Anniversary Edition Telescope