Amateur Telescope Making in Portland & Beyond Peter Abrahams. 1999. This article was written for submission to Sky & Telescope, but rejected because the 'Focal Point' column does not print rebuttals to the column. At the end is a list of some of the more creative ATM projects in my local area. ========================== The February 1999 issue of Sky & Telescope contained a guest editorial about a perceived decline in amateur telesope making. Reports of the demise of ATM are greatly exaggerated. The construction of astronomical equipment by amateurs is very much alive and well. Consider the variety of printed references available. There are now 10 books listed in Willman Bell's catalog that are specifically about telescope making, Edmund offers two more, and a thirteenth has recently been published in England. There are other books available on telescope design, the construction of observatories, and making CCD cameras. The Amateur Telescope Making Journal is devoted to the subject (2500 15th Ave. West, Seattle, WA 98119, USA; email mailto:webmaster@atmjournal.com; ). Amateur Astronomy magazine covers a variety of TM topics. Sky & Telescope published 15 articles related to TM in 1998, including innovations such as a folded Gregorian and a long focus Cassegrain. There are many foreign language publications with some ATM content, and at least a few books in German on the subject. It seems unlikely that at any time in the past there was this variety of published material on ATM. The number of web sites listed as the result of a search for "amateur telescope making" totals over 1,100 (some are duplicate entries), and certainly a sizable fraction of those have some useful content. Some of them document one maker's project; others are a club effort, and some try to be an encyclopedia on the subject. 'Astromart' and other web sites sponsor forums where ATM work is discussed. There are at least three e-mail lists on ATM, and the 'ATM list / ATM digest' has about 1,300 subscribers from around the globe. List signup instructions are at . The 'archives' of this list can modestly be described as huge, contain a vast amount of mostly accurate information on telescopes & optics, and are easily searchable at These 'global' resources for ATM are widely used, and easily accessed; and those who feel that telescope making is on the decline surely feel that way in spite of this massive documentation. These resources are not the reason that I believe ATM is more widespread and at a more advanced level than in earlier times. My perception is based on what I see at west coast amateur astronomy events, including Riverside, Oregon Star Party, Table Mountain (Washington) Star Party, and the Bellingham, Washington ATM conference. I see dozens of finely crafted, amateur-made telescopes at these events, and at least a few truly innovative instruments at each. The greatly increased sales of commercial telescopes can make these home-made scopes harder to see, but they are very apparent in my area. (I also see photos of Stellafane, Winter Star Party, and Astrofest, with plenty of evidence of ATM projects.) However, what I see most is the activity in Portland, Oregon, undertaken by the Rose City Astronomers. Some of their recent innovative projects include these: The most dramatic effect of ATM work in recent years has been in increasing the size of amateur telescopes. In the Portland area, two 30 inch Newtonians have been made, one 40 inch, and in Washington a 41 inch telescope was built. The 40 & 41 inch mirrors were owner-made. Two members have made great advances in ultra light Dobsonians. A very well engineered 18 inch weighs 85 pounds and can be seen at . Another finely made, 83 pound, 20 inch dob is described at < http://zebu.uoregon.edu/~mbartels/ul-dobs/ul-dobs.html>. Other progressive makers who have 'pushed the envelope' of portability can be found at the last site, including a 16 inch that weighs 40 pounds. Although it is not difficult to make a scope of balsa wood, or to cut big holes in a heavy telescope; these makers are building very rigid structures, and utilizing new designs for mirror cells to permit very thin mirrors. Other advances in portability include nesting the components of the telescope for travel. A telescope can be transported in a cube just a few inches larger than the diameter of the mirror. These telescopes have been built in many areas, with much sharing of designs thorough web pages, and a local telescope maker has specialized in their construction. Computer control of telescopes has been explored by several amateurs in my area, who have written software and assembled sensors, wires, and motors into very accurate drive systems. I have had the privilege of viewing at 2,000 power, using a 20 inch scope during a very fine high desert night, and the nebula remained precisely mid-field, with no stepping or vibration visible. Another amateur made telescope has been programmed to give a high magnification tour of the Veil nebula, smoothly moving around the periphery. The Northwest Astronomy Group is building an observatory west of Portland, with a 24 inch Cassegrain built around a commercial mirror. They are half way towards completion of a remote controlled system, using the internet to control the telescope and download CCD images. A 13 inch binocular Dobsonian was built in Portland, using matched, amateur- made mirrors. At least two or three dozen binocular telescopes have been built by other amateurs in the U.S., mostly using variations on the Dobsonian mount & Newtonian optics, but including other optical systems. A very innovative Newtonian binocular was made in Eugene, Oregon, with both mirrors in one tube, and inter-ocular adjustment accomplished by vertically offsetting the oculars. An 8 inch Houghton was built recently in Portland. This catadioptric design is ideal for an amateur built astro-camera, since it has spherical surfaces & is very 'forgiving' of errors. This maker is now working on a 20 inch Cassegrain. He is well on his way to completing an amateur made adaptive optics system, with 5 terms of correction: tip, tilt, focus, and 2 of astigmatism. A local craftsman built an electric kiln for glass work, and melted a few mirror blanks, up to 25 inches in diameter. A Portland-based ATM had plate glass cut into two discs and a quantity of small rectangles, and used the kiln to fuse them into a cellular mirror blank, which was slumped to the correct radius of curvature. This technique has been extensively explored by a Los Angeles area ATM, who is now focusing on thin slumped mirrors, supported by his own design of mirror cell, derived through finite element analysis. Construction has begun on another glass kiln in Portland, devoted to mirror blanks. Two members have made ceramic mirrors with cellular backs of various honeycomb patterns. Both slumped sheet glass and ceramic glaze have been used for the reflecting surface, and successful experiments with glaze show that it can melt to a smooth, glassy surface. A 10 inch mirror has been completed and coated, with a smooth spherical figure. A 16 inch mirror used larger cells in the back and suffered print-through. These are extremely light weight mirrors that cool very rapidly and will be very inexpensive to make. A local ATM has begun construction of a telescope tube that somewhat resembles the 'tensegrity' structures. An upper ring is connected to the rocker box by two spring mounted poles and a system of non-stretching cord. I place this in the 'experimental' category, but like the projects described above, it is a well-grounded effort, undertaken by technical pro who has the background to accomplish it. CCD projects have become part of ATM in recent years, and Salem, Oregon hosts a major annual conference on amateur CCD imaging. Many homebuilt cameras and telescopes dedicated to those cameras have been displayed, discussed, and used as inspiration for future projects. There is a respected place in ATM for those who just want a telescope and don't want to spend any money on it. There have been many people in this area who have assembled iron pipe, scrap metal, wood, and an old mirror, into a functioning tool for exploring the skies. Finally, Portland, Eugene, and Seattle, among other northwest cities, have active telescope making workshops. Between 3 and 30 people attend our sessions, two or three a month. There is plenty of grinding, polishing, and testing; also soldering, sanding, and assembling; with a pervasive undercurrent of pontificating, opinionating, and hot air. Seattle is certainly part of our regional growth, but as a major metropolitan area it has a long & busy history of ATM activities, culminating in a very active group of today, an account of which would fill another article. It could be noted that the ATM tradition at the Riverside Telescope Maker's Conference was revived in recent years, almost singlehandedly, by a Seattle amateur who drives 2400 miles round trip with the mirror blanks and buckets of grit. Bellingham is just north of Seattle and hosts an annual Telescope Optics Workshop attended by about 80 people, with much hands-on fabrication & testing, along with presentations (31 March - 2 April , 2000, ). ATM activity in Portland and the Northwest dates back to the 1930s. The Brown Foundation of Walla Walla Washington had a truck fitted with an equatorially mounted 10 inch f13 refractor as a mobile observatory, and toured the Pacific Northwest in the mid 1930s. At that time, an active Amateur Telescope Maker's Association was housed at Gonzaga University in Spokane. In the 1940s, Harold Haggart built an observatory in Oregon City with a 20 inch telescope with various foci: Cassegrain, Springfield, modified Coude, Prime, and Newtonian, on several sides of the tube. Circa 1960, he developed and sold the "Haggart Aquila" 6 inch Newtonian Maksutov. In the mid 1960s, a public observatory in Goldendale, Washington, with a 24 inch amateur made Cassegrain, was built with regional assistance. In that era, Portland amateurs made a series of optical flats, and independently devised the dry ice cold camera. In the 1960s, a solar observatory was built by Portland amateurs at a community college, with a roof that was flooded with water, and equipped with 6 inch projection optics designed for teaching. In the 1980s, another public observatory was built near Oregon City with a 24 inch ATM telescope, and the construction of Dobsonians became very popular. The University of Oregon's Pine Mountain Observatory started a program of amateur use of their facilities. Throughout those years, amateurs built their pipe mounts for their 6 and 8 inch reflectors, made refractors, and built backyard observatories. There was fine work in fair quantity, but I think we are typical in that ATM work has greatly developed into a diverse and technically advanced activity in the recent past. In the 50's and 60's, the astronomical community in the Portland area consisted of an average of 50 to 60 members, and probably 10 or so were active ATMs. Now we have nearly 400 members, and there are about 50 who have recently been active in ATM. Regionalism & local pride have little place in astronomy, which is directed off the earth. This article has discussed regional activities because they are evidence of a thriving field of endeavor. I do not think that the rainy Northwest is unique in these accomplishments. The Southwest is the observing center of the U.S., and there are many amateur telescope projects in that area. The evidence on-line is that the phenomenon is global. There have been changes in ATM activity. There are fewer Maksutovs & interesting catadioptric designs built, and possibly fewer Schiefspieglers and other tilted component telescopes (though I see a few of them at the Washington events). Most makers desire a maximum of aperture instead of an exotic design. There might be fewer observatories built, since many people live in light polluted areas (no doubt any decline in ATM is mostly due to the steady advance in light polluted skies.) Most of the manufacturers of mirror cells, focusers, diagonals, etc. don't seem to be able to afford advertisements in the major magazines and are subject to more than the average number of business failures. Sellers of optical surplus are plenty, but they all seem to be on-line. Changes are apparent when comparing S & T from the 1960s to that of today: there were more articles submitted by ATMs back then, describing their projects and problems, and there were no articles on the demise of ATM, to discourage beginners and encourage detractors. These changes will continue, and bigger changes will happen as telescope design evolves around the CCD chip. Someday, amateurs will have orbiting space telescopes. For now, we live in a time of opportunity and accomplishment, when motivated individuals can construct a telescope of a caliber that would have been unimaginable a short time ago. ======================= Recent Portland area or RCA member projects. --Dan Gray, computer control, image rotator, tensioned 'truss tube', fused cellular glass mirror, & glass kiln --Greg Jones, 8 inch Houghton, 20 inch Cassegrain, adaptive optics --Rob Brown, ceramic mirror, cellular back --Steve Swayze, binocular telescope, 40 inch telescope --Bob Bond, 'stroboscopic' viewer for Crab pulsar --Rebecca Gee, experiment with 4 colors of LEDs & dark vision --Steve Stadleman, kiln for melting glass blanks --Dan Stixrud, Vancouver WA. Mouse optical encoder 'hacked' into telescope 'setting circles' --Dan Peterson, electric collimator assembly (tilts primary from eyepiece) --Greg Babcock, ultra light telescope --Mel Bartels, ultra light, computer control --Chuck Dethloff, 'frequent flyer telescope', portable