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.
A Ritchey–Chrétien telescope is a specialized variant of the Cassegrain telescope that has a hyperbolic primary mirror and a hyperbolic secondary mirror designed to eliminate off-axis optical errors (coma). The RCT has a wider field of view free of optical errors compared to a more traditional reflecting telescope configuration. Since the mid 20th century, a majority of large professional research telescopes have been Ritchey–Chrétien configurations; some well-known examples are the Hubble Space Telescope, the Keck telescopes and the ESO Very Large Telescope.
Yerkes Observatory is an astronomical observatory located in Williams Bay, Wisconsin, United States. The observatory was operated by the University of Chicago Department of Astronomy and Astrophysics from its founding in 1897 to 2018. Ownership was transferred to the non-profit Yerkes Future Foundation (YFF) in May 2020, which began restoration and renovation of the historic building and grounds. Re-opening for public tours and programming began May 27, 2022.
The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a 1,740-meter (5,710-foot) peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles.
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.
A reflecting telescope is a telescope that uses a single or a combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century by Isaac Newton as an alternative to the refracting telescope which, at that time, was a design that suffered from severe chromatic aberration. Although reflecting telescopes produce other types of optical aberrations, it is a design that allows for very large diameter objectives. Almost all of the major telescopes used in astronomy research are reflectors. Many variant forms are in use and some employ extra optical elements to improve image quality or place the image in a mechanically advantageous position. Since reflecting telescopes use mirrors, the design is sometimes referred to as a catoptric telescope.
The Dominion Astrophysical Observatory, located on Observatory Hill, in Saanich, British Columbia, was completed in 1918 by the Canadian government. The Dominion architect responsible for the building was Edgar Lewis Horwood. The main instrument is the 72-inch-aperture (1.83 m) Plaskett telescope, proposed and designed by John S. Plaskett in 1910 with the support of the International Union for Cooperation in Solar Research.
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.
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.
The BTA-6 is a 6-metre (20 ft) aperture optical telescope at the Special Astrophysical Observatory located in the Zelenchuksky District of Karachay-Cherkessia on the north side of the Caucasus Mountains in southern Russia.
The Vainu Bappu Observatory is an astronomical observatory owned and operated by the Indian Institute of Astrophysics. It is located at Kavalur in the Javadi Hills, near Vaniyambadi in Tirupathur district in the Indian state of Tamil Nadu. It is 200 km south-west of Chennai and 175 km south-east of Bangalore.
Big Bear Solar Observatory (BBSO) is a university-based solar observatory in the United States. It is operated by New Jersey Institute of Technology (NJIT). BBSO has a 1.6-meter (5.2 ft) clear aperture Goode Solar Telescope (GST), which has no obscuration in the optical train. BBSO is located on the north side of Big Bear Lake in the San Bernardino Mountains of southwestern San Bernardino County, California, U.S., approximately 120 kilometers (75 mi) east of downtown Los Angeles. The telescopes and instruments at the observatory are designed and employed specifically for studying the activities and phenomena of the Sun.
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 has some of the darkest skies on Long Island.
Obsession Telescopes is an American telescope company which specializes in the production of Dobsonian telescopes. The company has been noted for releasing the first truss commercially available Dobsonian telescope. It is also the largest producer of Dobsonian telescopes, and has worldwide operations.
The James Gregory Telescope was constructed in 1962 by the University of St Andrews. It is of a Schmidt-Cassegrain design and is fitted with a CCD camera. The telescope has very large field of view, compared even to regular 'wide field' designs, and can view 5 square degrees.
Yerkes 41-inch reflector is a 40-inch aperture (101.6 cm) reflecting telescope at the Yerkes Observatory, that was completed in 1968. It is known as the 41 inch to avoid confusion with a 40 inch refractor at the observatory. Optically it is a Ritchey–Chrétien design, and the main mirror uses low expansion glass. The telescope was used as a testbed for an adaptive optics system in the 1990s.
