|
The field of amateur telescope making is considered an offshoot of the amateur astronomy community. Amateur telescope makers (sometimes called ATMs), as their name implies, are not paid professionals. They build their telescopes for the enjoyment of the hobby, or so they can make a personal contribution to the field of astronomy. Image File history File linksMetadata Download high resolution version (540x700, 104 KB) Summary Description: A large trailer mounted Newtonian reflector on display at Stellafane in the early 1980s. ...
Image File history File linksMetadata Download high resolution version (540x700, 104 KB) Summary Description: A large trailer mounted Newtonian reflector on display at Stellafane in the early 1980s. ...
Newtonian Telescope The Newtonian telescope is a type of reflecting telescope invented by the British scientist Sir Isaac Newton (1643-1727), using a parabolic primary mirror and a flat diagonal secondary mirror. ...
The Stellafane Convention is a gathering of amateur telescope makers and amateur astronomers (star party) every year in Springfield, Vermont, conducted by the Springfield Telescope Makers. ...
It has been suggested that this article or section be merged with Skygazing. ...
This article does not cite any references or sources. ...
A hobby is a spare-time recreational pursuit. ...
For other uses, see Astronomy (disambiguation). ...
The Beginnings of a “Hobby” Ever since Galileo took a Dutch invention and adapted it to astronomical use, telescope making has been an evolving discipline. Many astronomers after the time of Galileo built their own telescopes out of necessity, but the advent of amateurs in the field building telescopes for their own enjoyment and education seems to have come into prominence in the 20th century.
Before the advent of modern mass produced telescopes the price of even a modest instrument was often beyond the means of an aspiring amateur astronomer. Building your own was the only economical method to obtain a suitable telescope for observing. There were many published works that also helped spark an interest in building telescopes, including Rev. William F. A. Ellison's 1920 book "The Amateur's Telescope" and several articles in Popular Astronomy by Russell W. Porter, including one appearing in March, 1923 about the Telescope Makers of Springfield. In 1925 Albert G. Ingalls featured Porter and the Springfield Telescope Makers. in an article he wrote for Scientific American magazine. There was so much public interest, a whole series of articles were written by Ingalls on the subject. Those articles (and later three books titled “Amateur Telescope Making” Vol. 1-3) helped people around the world take on the task of constructing their own instruments. In the US, the ready supply of surplus optical components after World War 2 and later Sputnik and the space race greatly expanded the hobby. Popular Astronomy is the quarterly magazine of the UKs Society for Popular Astronomy. ...
The Porter Garden Telescope, designed by Porter as a garden feature, much like a sundial. ...
Albert Graham Ingalls (January 16, 1888–August 13, 1958) was an American astronomer and editor. ...
Scientific American is a popular-science magazine, published (first weekly and later monthly) since August 28, 1845, making it the oldest continuously published magazine in the United States. ...
Sputnik 1 The Sputnik program was a series of unmanned space missions launched by the Soviet Union in the late 1950s to demonstrate the viability of artificial satellites. ...
For other uses, see Space Race (disambiguation). ...
"The Poor Man's Telescope" The types of telescopes that amateurs build vary widely. They range from the very simple to complicated designs including Refractors, Schmidt Cassegrains and Maksutovs. The most popular telescope design is the Newtonian reflector, described by Russell W. Porter as “The Poor Man's Telescope”. The Newtonian has the advantage of being a simple design that allows for maximum size for the minimum expense. And since the design employs a single front surface mirror as its objective it means (for the person creating the optical elements) that there is only one surface that has to be ground and polished, as opposed to three for the Maksutov and four for the refractor and the Schmidt-Cassegrain. A properly designed and built Newtonian is a high performance instrument, fully capable of matching the performance of other designs, a case where inexpensive does not mean inferior. Typically a Newtonian Telescope of 6” or 8" (15 or 20cm) aperture is considered a good starter project. Some widely available plans found on the Internet include instructions for building 6", 8", and 10" Newtonians. Image File history File linksMetadata Download high resolution version (616x800, 106 KB) Summary Description: Several 6†Newtonian reflector telescopes built by a school students as part of a class project on display at Stellafane in the early 1980s. ...
Image File history File linksMetadata Download high resolution version (616x800, 106 KB) Summary Description: Several 6†Newtonian reflector telescopes built by a school students as part of a class project on display at Stellafane in the early 1980s. ...
Newtonian Telescope The Newtonian telescope is a type of reflecting telescope invented by the British scientist Sir Isaac Newton (1643-1727), using a parabolic primary mirror and a flat diagonal secondary mirror. ...
Image of a refracting telescope from the Cincinnati Observatory in 1848 A refracting or refractor telescope is a dioptric telescope that uses a lens as its objective to form an image. ...
Schmidt-Cassegrain The Schmidt-Cassegrain, invented by Bernhard Schmidt, is similar to the Cassegrain. ...
Named after Russian optician Dmitri Maksutov (1896-1964), the Maksutov telescope is a type of Cassegrain reflecting telescope that uses a spherical primary mirror in conjunction with a meniscus-shaped correcting plate at the entrance pupil in order to correct for spherical aberration. ...
Newtonian Telescope The Newtonian telescope is a type of reflecting telescope invented by the British scientist Sir Isaac Newton (1643-1727), using a parabolic primary mirror and a flat diagonal secondary mirror. ...
The Porter Garden Telescope, designed by Porter as a garden feature, much like a sundial. ...
Several objective lenses on a microscope. ...
Image of a refracting telescope from the Cincinnati Observatory in 1848 A refracting or refractor telescope is a dioptric telescope that uses a lens as its objective to form an image. ...
Schmidt-Cassegrain The Schmidt-Cassegrain, invented by Bernhard Schmidt, is similar to the Cassegrain. ...
Newtonian Telescope The Newtonian telescope is a type of reflecting telescope invented by the British scientist Sir Isaac Newton (1643-1727), using a parabolic primary mirror and a flat diagonal secondary mirror. ...
a big (1) and a small (2) aperture For other uses, see Aperture (disambiguation). ...
Mirror making Since the Newtonian Reflector is the most common telescope built by amateur telescope makers, large sections of the literature on the subject are devoted to fabrication of the primary mirror. The mirror has to be carefully "figured" to an extremely accurate shape, usually a paraboloidal, although telescopes with high focal ratios may use spherical mirrors since the difference in the two shapes is insignificant at those ratios. The tools used to achieve this shape are surprisingly simple, consisting of a of similarly sized glass "tool", a series of finer abrasives, and a polishing "pitch lap" made from a type of tree sap. Through a whole series of random strokes the “mirror” becomes a perfect spheroidal section. At that point it only takes a slight variation in polishing strokes to create the desired paraboloidal shape. Newtonian Telescope The Newtonian telescope is a type of reflecting telescope invented by the British scientist Sir Isaac Newton (1643-1727), using a parabolic primary mirror and a flat diagonal secondary mirror. ...
A parabola A graph showing the reflective property, the directrix (light blue), and the lines connecting the focus and directrix to the parabola (blue) In mathematics, the parabola (from the Greek: παÏαβολή) (IPA pronunciation: ) is a conic section generated by the intersection of a right circular conical surface and a plane...
A 35mm lens set to f/11, as indicated by the white dot above the f-stop scale on the aperture ring In photography the f-number (focal ratio) expresses the diameter of the diaphragm aperture in terms of the effective focal length of the lens. ...
Foucault test The equipment most amateurs use to test the shape of the mirrors, a Foucault tester, is, like the tools used to create the surface, simple to fabricate. At its most basic it consists of a light bulb, a piece of tinfoil with a pinhole in it, and a razorblade. ...
The light bulb is one of the most significant inventions in the history of the human race, illuminating the darkness of the evening and bringing light indoors at all times in order focus on the task at hand. ...
 Foucault test setup to measure a mirror
 Shadowing on the surface of the mirror as it appears during Foucault testing, depending on knife-edge position After the mirror is polished out it is placed vertically in a stand. The Foucault tester is set up at a distance close to the mirror's radius of curvature. The tester is adjusted so that the returning beam from the pinhole light source is interrupted by the knife edge. Viewing the mirror from behind the knife edge shows a pattern on the mirror surface. If the mirror surface is a perfect spheroid, the mirror appears evenly lighted across the entire surface. If the surface is paraboloidal, the mirror looks like a donut or lozenge. It is possible to calculate how closely the mirror surface resembles a perfect paraboloid by placing a special mask over the mirror and taking a series of measurement with the tester. This data is then reduced and graphed against an ideal parabolic curve. Download high resolution version (1000x415, 48 KB) Description: The Foucault knife-edge mirror test Source drawn on 2004 March 11 Artist ArtMechanic File links The following pages link to this file: Amateur telescope making User:Wikibob/Images Categories: GFDL images ...
Download high resolution version (1000x415, 48 KB) Description: The Foucault knife-edge mirror test Source drawn on 2004 March 11 Artist ArtMechanic File links The following pages link to this file: Amateur telescope making User:Wikibob/Images Categories: GFDL images ...
Download high resolution version (1000x400, 50 KB) Description: The Foucault knife-edge mirror test appearance depending on knife-edge and focus relative positions Source: drawn on 2004 March 11 Artist: ArtMechanic File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old...
Download high resolution version (1000x400, 50 KB) Description: The Foucault knife-edge mirror test appearance depending on knife-edge and focus relative positions Source: drawn on 2004 March 11 Artist: ArtMechanic File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old...
Some ATMs use a similar test called a Ronchi test that replaces the knife edge with a grating comprising several fine parallel wires. In optical testing a Ronchi test is a method of determining the figure of a mirror used in telescopes and other optical devices. ...
Aluminizing or "silvering" the mirror Once the mirror surface has the correct shape a very thin coating of a highly reflective material is added to the front surface.
Historically this coating was silver. Silvering was put on the mirror chemically. This was then polished. Silvering was typically done by the mirror maker. Silvering is the chemical process of coating glass with a reflective substance, originally silver, in order to create a mirror. ...
Since the 1950s most mirror makers have the coating applied by a firm specializing in the work. Modern coatings usually contain Aluminium and other compounds. The 1950s decade refers to the years 1950 to 1959 inclusive. ...
Aluminum redirects here. ...
The mirror is aluminized by placing it in a vacuum chamber with electrically heated tungsten or nichrome coils that can sublime aluminium. In a vacuum, the hot aluminium atoms travel in straight lines. When they hit the surface of the mirror, they cool and stick. Some mirror coating shops evaporate a layer of quartz onto the mirror, others expose it to pure oxygen or air in an oven so that it will form a tough, clear layer of aluminium oxide. This article does not cite any references or sources. ...
Telescope design
 A large fork mounted telescope and several other amateur built telescopes on display at Stellafane The telescopes amateur telescope makers build range from backyard variety to sophisticated instruments that make meaningful contributions to the field of astronomy. Instruments built by amateurs have been employed in planetary study, astrometry, photometry, comet and asteroid discovery to name just a few. Even the “hobbyist” end of the field can break down into several distinct categories such as: observing deep sky objects, observing the planets, solar observing, lunar observation, and astrophotography of all those class of objects. Therefore the design, size, and construction of the telescopes vary as well. Some amateur telescope makers build instruments that, while looking crude, are wholly suited to the purpose they are designed for. Others may strive for a more aesthetic look with high levels of mechanical “finish”. Since many amateur telescope makers do not have access to high-precision machining equipment, many elegant designs such as the Poncet table, Crayford focuser, and the Dobsonian telescope have evolved, which achieve extreme precision and stability without requiring strict tolerances in machining. Image File history File linksMetadata Download high resolution version (488x700, 101 KB) Summary Description: A large fork mounted telescope and several other amateur built telescopes on display at Stellafane in the early 1980s. ...
Image File history File linksMetadata Download high resolution version (488x700, 101 KB) Summary Description: A large fork mounted telescope and several other amateur built telescopes on display at Stellafane in the early 1980s. ...
The Stellafane Convention is a gathering of amateur telescope makers and amateur astronomers (star party) every year in Springfield, Vermont, conducted by the Springfield Telescope Makers. ...
For other uses, see Astronomy (disambiguation). ...
Illustration of the use of optical wavelength interferometry to determine precise positions of stars. ...
In astronomy, photometry is the measurement of the flux or intensity of an astronomical objects electromagnetic radiation. ...
Deep sky is a term used by amateur astronomers to describe mostly faint objects outside the solar system like star clusters, nebulae and galaxies; compare with deep space. These objects are hundreds to billions of light years distant. ...
Astrophotography is a specialised type of photography that entails making photographs of astronomical objects in the night sky such as planets, stars, and deep sky objects such as star clusters and galaxies. ...
There are very few or no other articles that link to this one. ...
A Dobsonian telescope on display at Stellafane in the early 1980s The Dobsonian telescope is a design that has become popular amongst amateur astronomers because it results in an extremely simple and rugged large-aperture instrument at low cost. ...
In recent years there has been an expansion in the commercial production of inexpensive and high quality mass-marketed telescope designs in the smaller 4" to 10" (10 to 25cm) apertures, making these instruments far more affordable. This has led to fewer amateurs building instruments in the smaller sizes, as it has become cheaper just to buy such a telescope.[citation needed] Most ATMs focus on building larger instruments, generally from 10" (25cm) up to designs as large as 30" (75cm) and beyond.[citation needed] Such an instrument can be built for less cost than it would cost to buy, and amateur made telescopes can surpass the quality and craftsmanship of commercially available telescopes.
The difficulty of construction is another factor in an amateur’s choice of project. For a given design the difficulty of construction grows roughly as the square of the diameter of the objective. For example a Newtonian telescope of 4 inch (100 mm) aperture is a moderately easy science fair project. A 6 inch (150) to 8 inch (200 mm) Newtonian is considered a good compromise size since construction is not difficult and results in an instrument that would be expensive to purchase commercially. A 12 inch (300 mm) to 16 inch (400mm) reflecting telescope is difficult, but still within the ability of the average amateur who has had experience building smaller instruments. Amateurs have constructed telescopes as large as 1 meter across (39 inches), but usually small groups or astronomy clubs take on such projects.
The Dobsonian: A case in point -
 An amateur built Dobsonian telescope of moderate size Since the overall design of a telescope tends to be an exercise in creative problem solving the types of instruments amateurs come up with can be unique to their field. A case in point is the Dobsonian telescope. John Dobson, the originator of the design, wanted an instrument fully optimized for deep sky observing. Since Dobson was a monk living in a monastery at the time, the telescopes he built had to meet the following criteria: A Dobsonian telescope on display at Stellafane in the early 1980s The Dobsonian telescope is a design that has become popular amongst amateur astronomers because it results in an extremely simple and rugged large-aperture instrument at low cost. ...
Image File history File links Download high resolution version (576x768, 162 KB) Newtonian telescope - classical form of Dobsonian using closed tube photographed by user:ECeDee date made: May 5, 2005 venue: VTT = Vogelsberg Teleskop-Treffen 2005 File links The following pages link to this file: Amateur telescope making ...
Image File history File links Download high resolution version (576x768, 162 KB) Newtonian telescope - classical form of Dobsonian using closed tube photographed by user:ECeDee date made: May 5, 2005 venue: VTT = Vogelsberg Teleskop-Treffen 2005 File links The following pages link to this file: Amateur telescope making ...
In astronomy the Dobsonian is a type of alt-azimuth telescope mounting that became popular among amateur astronomers in the 1980s because of its extreme simplicity, low price, and rugged construction. ...
A Dobsonian telescope on display at Stellafane in the early 1980s The Dobsonian telescope is a design that has become popular amongst amateur astronomers because it results in an extremely simple and rugged large-aperture instrument at low cost. ...
John Dobson in Wellington, New Zealand, April 2005 John L. Dobson (born September 14, 1915) is a highly influential amateur astronomer who has been dubbed the pied piper of astronomy and the star monk. He was the only amateur astronomer highlighted in the PBS series The Astronomers, and appeared twice...
Deep sky is a term used by amateur astronomers to describe mostly faint objects outside the solar system like star clusters, nebulae and galaxies; compare with deep space. These objects are hundreds to billions of light years distant. ...
- it had to be as large as possible
- it had to be easy to build
- it had to be constructed with commonly available materials
- it had to be inexpensive
- it had to be durable
- it had to be portable (to get to dark sky locations)
His solution was not only a unique design, it also consequently caused a quantum leap in the size of instruments that amateurs build. Based on a simple design the telescope does away with the complex and cumbersome equatorial mount that was typical for earlier telescopes. A simple mount made of plywood, with Teflon bearings allows the telescope to move in azimuth (left and right) and elevation (up and down). The design has proven to be easy to build and highly adaptable. Amateur builders continue to tinker with and improve the design in the true spirit of the amateur telescope maker. The equatorial coordinate system is probably the most widely used celestial coordinate system, whose equatorial coordinates are: declination () right ascension () -also RA-, or hour angle () -also HA- It is the most closely related to the geographic coordinate system, because they use the same fundamental plane, and the same poles. ...
In chemistry, polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer which finds numerous applications. ...
A bearing is a device to permit constrained relative motion between two parts, typically rotation or linear movement. ...
Azimuth is the horizontal component of a direction (compass direction), measured around the horizon, from the north toward the east (i. ...
Telescope making books and other published information
 A 180mm Texereau standard telescope - Albert G. Ingalls (ed.), Amateur Telescope Making (Vols. 1-3). Orig. edition: Scientific American; new rearranged edition: Willmann-Bell Inc.
- Allyn J. Thompson, Making Your Own Telescope, 1947, Sky Publishing, ISBN 0-933346-12-3.
- Jean Texereau, How to Make a Telescope, Willmann-Bell, ISBN 0-943396-04-2
- David Kriege, Richard Berry, The Dobsonian Telescope: A Practical Manual for Building Large Aperture Telescopes, 1997, Willmann-Bell, ISBN 0-943396-55-7
- Richard Berry, Build Your Own Telescope, Willmann-Bell, ISBN 0-943396-69-7
- Harrie Rutten, Martin van Venrooij, Telescope Optics, Evaluation and Design, Willmann-Bell, ISBN 0-943396-18-2
Image File history File links Metadata Size of this preview: 396 × 600 pixelsFull resolution‎ (2,500 × 3,787 pixels, file size: 3. ...
Image File history File links Metadata Size of this preview: 396 × 600 pixelsFull resolution‎ (2,500 × 3,787 pixels, file size: 3. ...
Albert Graham Ingalls (January 16, 1888–August 13, 1958) was an American astronomer and editor. ...
-1...
See also It has been suggested that this article or section be merged with Skygazing. ...
Group 70 is a non-profit educational organization comprised of people from many countries all around the world and many walks of life seeking to make the beauty of astronomy available to the peoples of the world. ...
Eight Inch refracting telescope. ...
The Stellafane Convention is a gathering of amateur telescope makers and amateur astronomers (star party) every year in Springfield, Vermont, conducted by the Springfield Telescope Makers. ...
References Albert Graham Ingalls (January 16, 1888–August 13, 1958) was an American astronomer and editor. ...
External links |
Feeds |
Contact