Amateur Telescope Making


In today's retail markets the amateur astronomer can choose from a wealth of telescopes, accessories and software from dozens of manufacturers and across all price points. One finds binoculars and small Dobsonian or refracting telescopes priced around $100 and professional quality Ritchey Chrétien or corrected Dall Kirkham astrographs priced at $20,000 or more — just for the optical tube assembly.

So it is sobering to recall that seven decades ago many amateur astronomers had to grind their own mirror or lens and construct the telescope tube and mounting with their own hands. Amateurs active during the early 20th century not only required an intense interest in astronomy, they also needed the self motivation, persistence and unique mechanical skills necessary to build their own astronomical instrument. Out of their collective but solitary craft emerged the robust and colorful tradition of amateur telescope making.

The origins of this tradition are probably lost forever, due to the improvisational design of amateur instruments and the repurposed materials used to make them. We do know that many naturalists of the 17th and 18th centuries (including Galileo, Huygens, Newton and Herschel) built their own optical instruments, and individuals with the reputation of telescope maker — George Henry With, James Short, George Calver, Alvan Clark — do not appear in numbers until the end of the 19th century. But as professional telescope makers became more common, amateur telescope makers grew numerous as well.

Workers with one of Parsons's 72" speculum mirrors

Before the mid 20th century, there is an unreliable distinction between the amateur and professional astronomer. The massive Leviathan of Parsonstown, one of the largest telescopes of the 19th century, was built at the midlife behest of the wealthiest of English amateur astronomers — William Parsons, 3rd Earl of Rosse — whose researches were as often interrupted by his duties as a member of Parliament and chancellor of Trinity College, Dublin, as by the cloudy Irish skies. Most features of the design and construction of this 16 ton telescope were innovated by Parsons himself, but the actual construction and maintenance were carried out by artisans who seem less like textbook engineers than rustic bodgers ... or members of an amateur telescope making society. William Lassell, pioneer of the equatorial mount, was a beer brewer; Andrew Ainsley Common, one of the first astrophotographers, was a sanitary engineer; Henry Draper pioneered stellar spectroscopy but was by day a physician. Rutten and van Venrooij (1988, p.5) comment: "Looking over the early history of telescopes, it is striking that many developments in telescope making are the result of the efforts of amateurs and other individuals not occupied professionally with astronomy."

But how valid is the distinction? Perhaps amateurs could be limited to only those telescope makers who were enrolled students or adults employed in any occupation other than astronomer, optical manufacturer or physicist. The complication is that many 19th and 20th century astronomers and telescope builders started their careers as amateurs. Russell Porter founded one of the earliest ATM societies and went on to help design the 5 meter Palomar telescope: was he amateur, or professional?

In this muddle, the expansive definition offered by George Ellery Hale (quoted in William Olcott's Field Book of the Skies, 1932, p.447) is helpful:

"The amateur is the man who works on Astronomy because he cannot help it, because he would rather do such work than anything else in the world, and who therefore cares little for hampering traditions, or for difficulties of any kind."

Naturalists, lawyers, doctors, educators, machinists, priests and parsons were disproportionately endowed with this spirit. And, amending Hale, one finds among amateur astronomers a significant number of women and young adults.

The number of amateur telescope makers in the United States began significantly to increase in the 1920's, due to three factors. A growing number of practical articles and guidebooks became available — in popular magazines such as The English Mechanic or Popular Science, in the Rev. Archdall Ellison's groundbreaking The Amateur's Telescope (1920), in the monthly column "Telescoptics" and then "The Backyard Astronomer" (1928) conducted by Albert Ingalls for Scientific American. The Ingalls columns were published as the first of the three volume Amateur Telescope Making in 1933. Frequent contributions were made by the architect and Arctic explorer Russell Porter, who began grinding his own mirrors after reading Ellison's book and with technical and financial support from a fellow ATM enthusiast, mechanical engineer James Hartness. Ellison, Porter and Ingalls contributed mightily to make complex optical issues and mechanical designs more practical and easily understood to the interested public, as part of the "do it yourself" meme of early 20th century print media.

The hobby was nurtured by high school and adult education classes in which experienced (self taught) amateur telescope makers guided the efforts of newcomers, some of whom went on to form their own amateur telescope maker groups. First in precedent and influence among these groups was the Springfield Telescope Makers of Vermont, initiated by Porter in 1920 as an adult class in telescope making, then organized by the students as an astronomical club in 1923. The STM built a small meeting house and turret observatory of Porter's design on a 30 acre plot of land that Porter owned at the top of nearby Breezy Hill. Christened "shrine to the stars", Stellafane remains a hub of amateur activity on the East Coast and the site of an annual telescope builder's convention.

The last factor in the growth of amateur telescope making was a small but essential segment of manufacturers and retailers who began catering to the needs of the market. Optical kits, especially glass mirror blanks (including surplus porthole glass) and grinding materials, and the basic parts necessary to make telescope focusing mechanisms and mountings began to be offered commercially and advertised in magazines by optical companies and machine manufacturers.

These three factors — publications, amateur groups and suppliers — contributed to the 20th century upswing in amateur telescope making, which was fueled also by a culture increasingly fascinated with science, technology and space.

Telescope makers remained active through the tough decades of the Depression and World War II. Economic hardship added impetus to the "do it yourself" mentality, and the wartime requisition of machine manufactories made the development of consumer optical equipment impractical. Despite those realities, interest in astronomy was sustained by the narrative of the slowly progressing Palomar Mountain telescope project — designed to be twice the aperture of the then largest telescope in the world, the 100 inch Mount Wilson telescope in California.

Concept drawing of the Mt. Palomar telescope by Russell Porter

Initial funding for the project was awarded by the Rockefeller Foundation in 1928, but the Palomar Mountain site was not selected, completed (at a total cost of $6.5 million) and dedicated until June, 1948. Those twenty years involved what was perhaps the largest amateur telescope project ever attempted. The design and casting of the mirror blank at the Corning Glass Works entailed significant failure and improvisation before it was successful. Several engineering innovations were necessary for the success of the "horseshoe" mounting, which is still a unique design among large telescopes. Hollywood movie editor Mark Serrurier designed the truss construction of the tube, and much of the mounting was built in a shipyard. The principal mover of the project was George Ellery Hale, an energetic serial telescope builder who was largely responsible for the 40" Yerkes refractor and both the 60" and 100" Mount Wilson reflectors. ATM visionary Russell Porter was recruited to the Palomar project in 1927, at Ingalls's suggestion, and contributed to the design of both the telescope mounting and the observatory building. His elegant pencil renderings of the mechanism — whether painstakingly dissected drawings of the mount, or sunlight dappled visions of the architectural concept (above) — were a key part of the developing Palomar romance.

The military service of readers during World War II forced two astronomy related magazine titles — The Sky and Telescope — to merge in November, 1941 as today's Sky & Telescope. This periodical included a few scholarly articles on astronomy by astronomers such as Otto Struve, and a monthly column "Gleanings for A.T.M.'s", conducted by Earle Brown, that discussed every aspect of amateur telescope design and construction. The magazine was also a premier venue for advertisers of amateur astronomy products, including telescope making supplies and the postwar wave of consumer telescopes.

During the Truman and Eisenhower years a flood of military surplus eyepieces, prisms, binoculars and objective lenses of all types poured into the consumer market via retailers such as A. Jaeger or Edmund Salvage Inc. — whose 1950 catalog states "never in history were so many optical items made as during the last war." Advertisements soon appeared in Sky & Telescope from vendors of telescope making supplies (C.C. Young), telescope making kits (David William Wolf, Precision Optical Supply) and professionally machined telescope mounts (Haines Scientific Instruments). In the late 1940's appeared the first postwar consumer telescopes — the 3.5" Sky-Scope Newtonian reflector for $25, and the 3" Tinsley Laboratory refractor for $199.

Advertisement for the film "Forbidden Planet" (1956)

Accompanying this increase in telescope making resources was a cultural focus on the reality of outer space. Space travel, new worlds, alien life forms and the intergalactic struggle for species supremacy were stereotypical science fiction themes. The V2 missile, cryptography, early computers and the atomic bomb had elevated the popular conception of science into (quoting Firesign Theater) "a force so powerful it can only be used for good or evil." Expatriate German rocket scientists in the United States laid the technical foundations for high altitude astronomical research, the intercontinental ballistic missile program, and the first satellites; rocket designs for human space travel were featured in two 1955 episodes of the Sunday night Walt Disney Presents narrated by Werner Von Braun. Flying saucers were first reported by an amateur pilot in 1948 and quickly migrated into popular awareness — they were visiting us! Interplanetary travel and alien contact were depicted in films such as The Day the Earth Stood Still (1951), The Thing From Another World (1951), This Island Earth (1955) and Forbidden Planet (1956). Meanwhile amateur astronomy grew apace: a 1954 Sky & Telescope directory listed almost 120 amateur astronomy groups in 35 states, led by California, Ohio, New York and Florida.

The 1950's was also the decade of mass commercial telescope manufacture for the amateur astronomer. The harbingers were two unbranded 1.6" and 2.4" refractor telescopes first marketed (for $75 and $225 respectively) by United Trading Co. in October 1951. The company adopted the brand name Unitron for these refractors in February, 1952 and a few months later registered anew as United Scientific Co. offering an equatorially mounted (and expensive) 3" Unitron refractor for $435. Edmund Scientific and Chester Brandon (later Brandon Instruments) were also active in 1952 selling eyepieces, mirrors and telescope components. By June 1954, when Questar offered its exquisite 3.5" Maksutov Cassegrain with blue enameled tube and maroon leather case for $795, the Unitron line had expanded to include seven refractors — from a 1.6" budget altazimuth to a 4" equatorial refractor at $785, with a variety of mountings and components for the amateur telescope maker. Around this time also appeared less expensive telescopes designed for lower income families and the children's educational market: the Criterion Co. 1.6" refractor ($26.95) and the 4" Dynascope reflector ($44.95).

A Unitron advertisement, circa 1955

In the mid 1950's the first medium aperture (6" to 12") Newtonian and Cassegrain reflecting telescopes came into the market. C.C. Young began advertising completed small reflectors in 1953; Cave Optical Co. (Long Beach, California) and J.W. Fecker, Inc. (Pittsburgh) began national advertising of completed 6" to 12.5" reflectors in 1954. Coast Instruments (Long Beach) closely imitated the Cave design with their 6" to 12" Treckerscopes first offered in 1956, and Criterion Manufacturing Inc. introduced their excitingly new! 6" to 16" Dynascopes in 1957, then the largest consumer Newtonian instruments available in the USA.

By 1957 Sky & Telescope was publishing a full page guide to 67 products or services offered by 42 astronomy retailers; its contact list of amateur astronomers had grown to 174 groups in 46 states. The sheer range in telescope quality and price points at the end of the decade — from the $98 Spacek Instrument Co. 4" reflector to the $6100 Unitron 6 inch "photoequatorial" refractor — signifies a fully matured consumer market. Although amateur telescope making remained a vibrant craft tradition (the third and last volume of Ingalls's ATM was published in 1954), amateur astronomy had expanded from a "do it yourself" hobby into a popular or status recreation ... depending on what you could afford to buy.

Telescope advertisements are fascinating testimony to the consumer values of the era. Questar ads highlighted the uncanny compactness, magical versatility and divine optical power of their sole and single 3.5" telescope: no optional parts, no aperture selection, no price range. Ads were often text heavy and technical: "On the Problem of Choosing a Telescope"; "Questar Guarantees 0.9-Sec. Resolution" (the theoretical limit is 1.1 arcseconds!); "A 3.5-Inch Questar Photographs the Solar Granulations From Sea Level". The appeal of quality over clutter, and the visual evidence of astronomical and wildlife photographs taken with a Questar, were also presented in artistic terms as the esthetic marriage of modern technology and painstaking craftsmanship — classical in its perfection.

A Questar advertisement, circa 1955

Unitron advertisements in contrast were blatantly aspirational and unapologetically conformist, announcing Unitron as the largest selling brand, the highest quality brand, the most popular brand ("the 'star' of the star party"), the brand with the most accessories (including the UniHex rotating eyepiece selector), the brand everyone is giving for Christmas, and most importantly (because a Unitron was expensive) the brand that offered attractive terms of down payment and financing. Remarkably, a single Unitron ad could simultaneously speak to the science minded teenager's expectations of his parents, the parent's self perceived obligation to their upwardly mobile children, and the adult's delayed gratification of his own childhood desires:

Johnny isn't watching the late show tonight ...
   The shadows that shiver and shake on the TV screen are shivering and shaking in somebody else's living room tonight. Johnny has discovered something new.
   He's traded the fleeting, flickering "thrills" of the 24 inch screen for the timeless excitement and majesty of the night sky. ...
   He has, in short, discovered astronomy.
   Nothing better could happen than what happened to Johnny. And it happened simply because someone took the trouble to awaken, nourish and satisfy a lifetime of curiosity in Johnny by making him the gift of a fine telescope.
   Someone, not so long ago, gave Johnny a Unitron.

Unitron ads frequently featured children and women as models; one ad even configured telescope components to make a zoo of fantastical animals. Astronomy had become as much a family as a solitary recreation, embraced by the rising class of affluent, educated and suburban professionals in management, science and technology, eager to impart a love of science to their children. This was also an era when even city dwellers enjoyed skies dark enough to make astronomy exciting, a backyard recreation ideally suited for a working father and his student son.

Despite the enormous increase in commercial astronomy products, the amateur telescope making movement was still very active, and making a telescope was my introduction to astronomy.

I received my first telescope at around the age of 7, an inexpensive 2.5" reflector of anonymous manufacture, little more than a cardboard tube and a ball mounting on three metal legs attached with annoyingly inefficient wingnuts. I sat with it on our suburban front lawn, watching the changing phases of the moon. A few years later, my family was on our first week's summer vacation trip in Sequoia National Park, and after a communal campfire singalong we encountered a man out observing the stars with a very large telescope of his own construction. That was the night I got my first clear and large scale view of Saturn and its glorious rings.

Allyn Thompson with a 6" telescope of his own construction

My interest in astronomy peaked at age 12 in 1961, when my dad and I built a 6" instrument after the instructions in Allyn J. Thompson's Making Your Own Telescope (1947), a slim brown volume of lore and guidance. I remember the peculiar smell of the resin as we applied fiberglas to the rolled steel tube my father had ordered from a local machine shop, and the itching on my arms caused by the fiberglas dust as we sanded the tube down for painting. We cast the lead counterweight in a coffee can and the babbitted bearings into the mounting made of lathe polished steel plumbing fixtures, then smoothed or "lapped" the bearings by laboriously twisting the axes back and forth with a mixture of oil and rotted stone. My dad, a hobbyist woodworker, made the tripod legs and tube mounting of hard maple. The finished result was almost identical to the telescope shown with Thompson on the October, 1945 cover of Sky & Telescope.

Cave Optical Co., circa 1960

Rather than shoulder the tedium and uncertain outcome of grinding the mirror and making the optical components ourselves, my dad purchased a 6" f/8 mirror, mirror mounting, diagonal, focuser and eyepieces from Cave Optical Co., by then nationally renowned for the quality of their optics and the engineering excellence of their equatorial mounts. The company served amateur, professional, university and government clients alike, and produced several large mirrors for NASA as well as some primary mirrors for Questar. They refigured amateur mirrors that had expired on the Foucault knife edge, and serviced for resale a variety of telescopes that they accepted as partial payment for a Cave instrument.

I remember the short drive, just 3 miles from my home, to Cave's small shop at 4137 East Anaheim St. in Long Beach. (It is now a small restaurant, Frenchy's Bistro.) Approaching from the street one saw large and small telescopes displayed in the flanking front windows, and through the glass front door one entered a spartan, linoleum tiled space, white walls bare of decoration except for a few photographs or celestial charts, two or three glass and metal display cases that seemed a bit large for the selective assortment of parts, eyepieces and books spread out on the shelves within. Through the open back passageway of this small sales room one could hear the occasional clang, grind and holler of telescope manufacture in the back, and through this door would occasionally appear Thomas Cave Jr. himself, whom I remember as tall, plainly dressed and helpful in a cordial but aloof manner.

Here one could see what real telescopes looked like, from small refractors up to massive specimens easily twice my size; here too one could browse books on astronomy unavailable in ordinary bookstores. At Cave Optical I purchased my first copy of Norton's Star Atlas and Telescopic Handbook, 14th Edition (1959), and encountered for the first time the beige linen bound deluxe edition of Antonin Becvar's ("Betch-varzh") Atlas Coeli Skalnate Pleso 1950.0, which dominated the shelf where it was displayed and completely consumed my interest. This was the period in which I first encountered and seriously explored Plato, Dante, Melville and other great authors: astronomy arrived at the moment my mind first became truly aware. As Russell Porter observed: "Surely the making and putting into use of a powerful astronomical telescope goes far toward properly orienting one's self in the great scheme of things."

My 10", f/8 Cave Astrola telescope. Pre owned by Krafft Ehricke, it is currently owned by an academic astronomer.

My astronomy activity continued unabated; I learned all the constellations, Messier objects and star typologies; I read Fred Hoyle's Astronomy (1962) cover to cover and pored over every page and chart of Norton's Star Atlas; I made my own moon drawings; I devoured astronomy topics (and the whimsies of Charles Fort) in books from the local library. So in 1963, at age 14, my parents bought me a deluxe 10" f/8 Cave Astrola telescope, with a ball bearing and chrome axis equatorial mount, electrical clock drive, white fiberglass tube mounted in convenient rotating rings, 6" diameter pier mounted on three roller legs, and four orthoscopic Cave eyepieces with a Barlow lens. The scope was "preowned" by Krafft Ehricke, then in California doing rocket engineering for the U.S. government, returned to Cave in trade for something bigger.

I spent many nights touring the skies with this fantastic instrument, out on the concrete back patio where my parents had built a swimming pool. Season by season, through junior and senior high school, I stayed out late tracking down whatever celestial landmarks the light pollution and air pollution of the Los Angeles conurbation would permit me to see. Eventually my interest turned to music, I studied the guitar, and built my own guitars and lute using my dad's workworking tools and skills he had taught me. The 6 inch OTA was stripped from its mount, the tube shortened and the mirror refigured by Cave as an f/4 RFT, then remounted on the opposite end of the declination axis, serving both as counterweight and richest field accompaniment to the 10 inch. Eventually high school romance and college completely diverted my interest, and I sold the Astrola to a local high school student in 1967 before I left home for the University of California, Irvine. So ended the first chapter of my astronomical interest ...

... with this postscript: a visitor to this site recently contacted me by email to announce he was the buyer of my telescopes 47 years ago. He still owns both the 10" and 6" reflectors, and is an astronomer with Jet Propulsion Laboratory.

Further Reading

The three classic texts on telescope making are Amateur Telescope Making (3 Volumes) by Albert Ingalls, Making Your Own Telescope by Allyn J. Thompson, and How to Make a Telescope by Jean Texereau.

A Little Amateur History by telescope maker R.F. Royce. – Dedicated to the Telescopes of Thomas Cave.

A Brief History of Stellafane by Bert Ward.

Classic Telescope Catalogs and Manuals compiled by Robert Provin.

The Porter Garden Telescope designed by Russell Porter and marketed in the 1920's.

Early Telescope Advertisements collected by Phil Harrington.

History of English Silvered Glass Reflecting Telescopes (mostly 19th century instruments) by Christopher Lord.

Prices In Current Dollars – For comparison to modern astronomical equipment, the prices in 2010 dollars of the telescopes described above are: 3.5" Sky-Scope Newtonian reflector ($205); 3" Tinsley Laboratory refractor ($1,640); Criterion Co. 1.6" refractor ($225); 4" Dynascope reflector ($370); Spacek Instrument Co. 4" reflector ($810); Unitron 1.6" refractor ($620); Unitron 2.4" refractor ($1,860); Unitron equatorially mounted 3" refractor ($3,540); Unitron equatorially mounted 4" refractor ($6,390); Unitron 6" photoequatorial refractor ($49,600); Questar 3.5" Maksutov Cassegrain ($6,470); Coast Instruments Deluxe 12.5" reflector ($8,950); Criterion Manufacturing 6" Dynascope reflector ($3,700); Cave Optical Standard Model Astrola 10" f/8 reflector without clock drive ($3,700); Cave Optical Deluxe Astrola 10" f/6 reflector with clock drive ($5,645).

Last revised 02/27/14 • ©2014 Bruce MacEvoy