Dmitri Dmitriyevich Maksutov was born in Nikolayev, Russia, on April 11, 1896. He expressed an interest in astronomy at an early age and at age fifteen he made a telescope with an18-centimeter mirror. Some time late he made an improved 21-cm reflector and made such extensive astronomical observations that they attracted the attention of the Russian Astronomical Society to which he was elected member at the age of fifteen. In 1913 he enrolled in the Military Engineering College in St. Petersburg, but in the following year classes were cancelled and he saw several years of military service in World War I and the Russian Revolution before he could return to his interest in optics.
During the 1920s and 1930s Maksutov first worked at the State Optical Institute in St. Petersburg, then the Odessa Observatory, the Odessa State Physical Institute, and finally back at the State Optical Institute.
But it was not until August, 1941 that he invented the class of telescopes for which he is most famous and the one that bears his name. It was patented in the U.S.S.R. according to the claim dated November 3, 19411. He discovered that a steeply curved meniscus lens in front of a spherical mirror could be made to introduce the correct amount of over corrected spherical aberration to balance the under corrected spherical aberration of the mirror. Even more remarkable, the single corrector lens could be made nearly achromatic with far less residual color than an equivalent achromat, and the entire telescope could be made coma free, with very small residual astigmatism. This concept of a single meniscus lens is so powerful that it may be applied to many types of telescopes; the Newtonian, Cassegrain, Gregorian, Mersenne, Schmidt, and even the subdiameter Ross-type corrector. The optical world first became aware of this exciting new type of telescope in Maksutov's paper published in the Journal of the Optical Society of America in May, 1944, "New Catadioptric Meniscus Systems," from which the following quotes are taken.
The high universality of the new systems assures their successful use in almost every branch of optical instrument making (geodesic, photographic, spectral, laboratory instruments, microscopes, and so on). However, this paper is written with the interests of astronomers in mind and will afford them the possibility of designing and making new instruments for amateur observations as well as for scientific ones. The present paper gives only the principal results, without theoretical derivations and details of design.
The principal role of the meniscus is the correction of spherical aberration and coma of spherical mirrors, without introducing a noticeable chromatism; however, in addition to that, the meniscus fulfills two very important functions. Firstly, it shuts the tube and makes possible a sealed instrument, free from convection streams, with mirrors well protected from dust, damage, and the influence of abrupt changes of temperature; secondly, the meniscus makes possible the fastening to it of secondary mirrors without supports, and often also without settings by means of an adhesive or by optical contact; in the most special case the central part of the inner surface of the meniscus may be aluminized and plays the role of a secondary mirror, the screening and the diffraction hindrances being in that case very small.1
In the present age of personal computers and optical design software capable of high-speed optimization and evaluation, it is difficult to imagine the countless hours of tedium facing the optical designer in Maksutov's day. To work out an understanding of this new family of telescope designs in the shortest amount of time he was required to trigonometrically trace the fewest possible rays that would reveal the performance of any particular design, then repeat the process, without errors, for as many variations as were being thought up. The only tools were logarithms and slide rules and it took several minutes to trace a single ray through several surfaces of a telescope.
Fortunately for the amateur, Maksutov's goal was to find designs simple enough to be produced cheaply in large numbers, meaning designs that required all spherical surfaces. These he found and in his paper he gave empirical formulae and tables that allowed one to select a particular design dependent upon the desired aperture. Surprisingly, he showed that visual telescopes could be designed corrected for spherical aberration, coma, and well achromatized, and have very low F/numbers. For example, for an aperture of 19.2 cm a telescope could be as fast as F/3.0.
Maksutov must have had access to western publications, for he recommended for his Herschelian version of the meniscus corrector telescope a "Springfield" type of mounting. He died in 1964.
Maksutov was not alone in inventing the meniscus corrector-spherical mirror telescope. During World War II other Europeans came up with the same idea, Albert Bouwers in the Netherlands, Karl Penning in Germany and Dennis Gabor in England. Bouwers finally published a small book, "Achievements In Optics," in 1950 describing his version of the meniscus corrector design for which he applied for a Netherland Patent on October 14, 1940. His Author's Preface begins:2
This monograph intends to give a survey of work on optics in the Netherlands during the last war or immediately before. Part of the results mentioned have already been published, but they have not of course penetrated into the English speaking countries. However, part of the work referred to was carried out secretly and the achievements were purposely not disclosed during the German occupation. The text was prepared and ready for printing before the liberation of our low countries. Owing to some purely technical reasons however, the appearance had to be postponed till about a year afterwards. So some papers on similar subjects as covered in this volume have not been paid attention to. Especially the article by Maksutov in the Journal of the Optical Society of America in May 1944 should have been referred to, since this author apparently obtained -- at a later date than the author of the present volume -- many of the results mentioned in the first chapters.
Remarkably, Bouwer's first experiments, done in August, 1940, were carried out with commercial meniscus spectacle glasses bought at an optician's. One was used as the corrector lens and the concave surface of the other was aluminized for the mirror. The arrangement worked nearly as fast as F/1, yet a photograph of a woman he showed is one to impress even the casual reader.
Unlike Maksutov who developed his designs empirically from laborious calculations, Bouwers worked through the paraxial equations governing how to balance the spherical aberration of a spherical mirror with a weak meniscus lens. Then he showed how the aperture stop could be moved to end up with a concentric system, one where the centers of curvature of the lens surfaces and the mirror are at the same point at the center of the stop. This eliminated coma, astigmatism, distortion, and lateral color since there was now no optical axis. This is a beautiful and simple concept, one characterized by only four parameters; the three radii of the concentric surfaces and the index of refraction of the lens. Bouwers had a flare for revealing hidden beauty in an optical design, perhaps only appreciated by an optical designer. One example was to point out in a drawing that the two principle planes of a concentric lens lie together in the plane of the center of curvature.
The primary detriment to the concentric meniscus-lens-mirror combination is that it has a small amount of chromatic aberration, yet this may be corrected by the single meniscus lens if it is adjusted to deviate somewhat from concentricity. The second method of achromatizing the meniscus lens is to split it with a flat surface that is "buried," meaning the glasses on both sides have the same nominal index but different dispersions. This is the method he used to construct a small 22x60 monocular fieldglass. Finally he presented his corrected concentric system that had a Schmidt aspheric corrector plate at the center of curvature of the concentric meniscus lens mirror combination. Only this time the aspheric corrector plate was very weak, its only role being to correct the slight higher order spherical aberration of the meniscus lens mirror combination.
Bouwers did not seem to have in mind the amateur interested in telescope systems; all the above theory was developed for the single mirror that is really a camera like the Schmidt system with its inaccessible and curved image surface. Finally, in a later chapter he presented a design, without specifications, for a Cassegrainian type astronomical telescope with the secondary mirror formed by an aluminized spot on the last surface of the meniscus lens. One important feature of his new type of telescope was the use of internal stops to completely eliminate unwanted stray light from reaching the image surface, something that Maksutov never mentioned even though he did mention the need for an external stop at the exit pupil of an astronomical eyepiece or an internal stop with a terrestrial eyepiece.
Lastly, Bouwers pointed out that the meniscus lens could be flipped over and placed on either side of the aperture stop and achieve the same correction. This led to the possibility of a Gregorian type telescope with its erect image for terrestrial use.
It did not take long for Albert Ingalls to hear about Maksutov's new telescope from advanced amateurs who had access to Maksutov's paper in JOSA. In the October, 1944 Telescoptics Department of Scientific American he reacted by enlisting amateur Norbert J. Schell, of Beaver Falls, PA, to study the design and report in the clearest possible manner to the amateur community the details of the exciting new telescope. By this time he had even found time to locate a source for lens blanks and got ten advanced amateurs to sign up for them: Norbert J. Schell from Beaver Falls, PA, Broadhead and Paul from western New York state, and King, Cristman, Luechinger, Franklin, Cameron, Thorne, and Rekouski all from the Long Island Astronomical Society. In the December, 1944 Telecsopes, Ingalls reported thirteen advanced amateurs had ordered 8.2-inch lens blanks from Corning Glass Works, while in the same issue Schell finished his discussion of the theory of correcting aberrations in the Newtonian-Maksutov telescope.
Ingalls reported3 that in 1945 Arthur DeVany of Des Moines, Iowa, had built a Maksutov for comet hunting, but it was never described in Scientific American.
In July, 1946, C.J. Tenukest, R. Shaefer, and H. Pinnock of New South Wales, Australia described in The Journal of the British Astronomical Association how they built their 6-inch Maksutov from data that Maksutov had provided in his 1944 paper in JOSA4.
Nearly two years passed since that first article in October, 1944 before the first report of a Maksutov made by an amateur appeared in Scientific American for October, 1947. G. Camilli, of Pittsfield, Massachusetts described building his 8-inch F/4 Newtonian-Maksutov following the specifications in the October, 1944 article by Schell. Then in the Amateur Astronomer page for December, 1949, David Broadhead of Wellsville, New York, described his Newtonian-Maksutov built according to the same specifications by Schell.
The Maksutov field appeared to lie fallow for several years until John F. Gregory became fascinated with the possibilities of this new telescope. Not content to build just another Newtonian-Maksutov, he had dreamed of a Cassegrain-Maksutov configuration. In Maksutov's 1944 paper4 he claimed to have computed, constructed, and tested successfully the Cassegrain system but gave no numerical details. He also suggested the secondary could be made by aluminizing the central spot on the inside surface of the corrector lens thus simplifying the construction. Such elimination of complexity appealed to John and he set about designing a Cassegrain-Maksutov using the principles set down by Maksutov. The success of his new design was firmly established when he brought his 5-inch F/20 "Mak" to the 1956 Stellafane convention and walked away with first prize for optical excellence.
John Gregory published an article in the March, 1957 issue of Sky and Telescope describing his new design for a Maksutov-Cassegrain telescope. He gave complete design specifications for 6-inch F/15 and F/23 telescopes. "The assembled telescope will perform so well that the amateur will be unable to find any fault, and will wonder why he waited so long to construct such an ideal instrument,"5 he wrote.
This was not John's first attempt at advanced optics. As a student in mechanical engineering at the Case Institute of Technology in Cleveland in 1949 he had designed and built a 5-inch Schmidt camera. The main parts of the fork mounted camera including the gearbox were aluminum for which he made the patterns and cast and machined the aluminum. The mirror he made from a 6-inch plate glass blank and had a 14-inch focal length. For the corrector plate he chose the design with the neutral zone at the .707 zone and used the test method described by Harold A. Lower in Amateur Telescope Making-Advanced, 1954 p.412, whereby a slit or Ronchi grating is placed at the focus and projected backward through the camera and the image is examined some distance in front of the camera, about 10 feet, with straight lines as one moves from side to side indicating a perfectly corrected system.
The same year that John Gregory brought his 5-inch "Mak" to the Stellafane convention, other people expressed interest in the new design and Allan Mackintosh stepped in and volunteered to form a Maksutov Club. But that part of the story is best told by Allan himself in the following letter.6
I have had a varied life. I was born in Inverness (Scotland) in March 1909 but my parents moved to London when I was about three months old as my father had bought a seat on the London Stock Exchange. The First World War made an upset in my family and my parents parted company in 1918 after I had been enrolled as a chorister at St. Paul's Cathedral; my voice broke in 1924 and I went to Dulwich College where I spent three years. When I left school I got a job as a bank clerk with the Bank of England but, after a year and a half I decided that the life was not for me and resigned. This coincided with the market crash in 1929 and I had great difficulty in getting another job, eventually I joined the Palestine Police in 1930, after I had taken a BA degree at London University (evening classes).
I stayed in Palestine until 1938 when I got a commission in the Colonial Police and was sent to the Bahamas. On arrival in the Bahamas I found that the commission was temporary so I applied for a transfer and got one to Jamaica. My job on leaving Palestine was sergeant in charge of the political section of the C.I.D. In Jerusalem, I had passed the government exam in Arabic and also had been called to the bar in London after three years of study in Palestine. I decided that anyone could do my job in Jamaica and resigned; this was in the middle of the "phony war" and on applying for a commission in the Army, I was told that there were "no vacancies". I had to get a job quickly so I applied to the U.S. Engineers Dept. who were then building the base in Jamaica to guard the Panama Canal and was put in charge of the native guards and watchmen for the base and made Justice of the Peace for the base and advisor to the Colonel Commander on native affairs.
I spent one of the best years of my life with the U.S.E.D., not least of which was that I met the American girl whom I later married. When the U.S.E.D. handed over the base to the U.S. Air Force, the commanding general in Puerto Rico decided that I was too expensive and cut my salary in half; I appealed to the Colonel who told me that I had been worth more than my salary to him but he could not do anything about it, so I resigned and put another application in for a British Army commission. The phony war had ended by this time (1942) and I got the commission and was sent to the Jamaica P.O.W. camp staff. After six months I was sent to a "commando course"; I had a look round and saw that most of the others on the course were about the early 20s and that either I would make the running or be an also ran. At the end of the course we were not told how we had finished but it was customary for the first to be given the choice of three stations to serve in, the second two stations and the rest where they were told. The Brigadier gave me a choice of three, but I asked him to send me over to Africa where the war was developing as I spoke Arabic and was trained in intelligence - he said that good officers were needed on this side also so I said that I would like to go to where I would be the most use, He grinned at me and said, "A soft answer turneth away wrath". At any rate I spent the next year in the Leeward Islands, mostly in Montserrat, a very pleasant island before the Soufriere volcano blew its top, but with short stops in St. Kitts and Anguilla.
In 1944 I was transferred back to the Bahamas where the quartermaster sergeant had embezzled mess funds. Somehow he had heard that I was a barrister and chose me as officer's friend; a court martial is a piece of cake for a trained lawyer and I got him acquitted. Two weeks later I was sent for by the Brigadier in Jamaica; he said, "You know he was guilty, don't you". I replied, "A client is always not guilty for his lawyer and I did my duty." He said, "Next time we will have you on our side, I am going to have you made judge-advocate". So I spent the rest of the war as substantive lieutenant, acting captain, local (unwanted) major.
From the Bahamas I managed to get a couple of leaves to New York where I married Helen, my American wife. When I was demobilized in 1946 she came to join me in Jamaica; I had begun a cabinet-making business - the only time I have ever made money in my life as there was only one other good cabinet maker in Jamaica and during the war he had become a prima donna - this was the time when a number of hotels were being built on the north shore of Jamaica so I cornered the market. Unfortunately Helen had had rheumatic fever as a child and her heart was badly damaged; in 1949 she became ill and I sent her back to New York to her doctors who said that she could not return to Jamaica. I sold out and joined her in New York, there were currency regulations in force so I could only take out £1000 which lasted a very short time what with doctors' bills.
I got myself a job as a warehouse supervisor with Ballantine's Brewery pushing beer down a shute. This was in May and I did not realize that it would come to an end with the hot weather. They laid me off in October and said that they hoped to see me next year. I got some short jobs over the Christmas period and in March I joined the Sperry Gyroscope as a D-grade parts inspector (the lowest form of animal life on the earth).
I did not mention that while I was in the Bahamas I picked up a copy of Scientific American where Albert Ingalls ran a page called, as I recall, Amateur Astronomer. I had always been interested in astronomy and sent for a kit and built a 6" reflector; it was a very bad one and I have kept the mirror to show me that I was not always so good as I am supposed to be. It took me six months to find out its shortcomings and when I did so, I sent for a 10" kit which turned out to be much better. I also joined Clyde Tombaugh's 16" club and took the blank all round the Caribbean (fortunately the army paid for my baggage)
On arrival in New York I joined the telescope making section of the A.A.A., then in the basement of the Hayden Planetarium, where I got to work on the 16" blank - I also became one of the class instructors. I also saw a copy of J.O.S.A. containing Maksutov's article on his telescope - this interested me more than a little.
In 1951 my wife died, she was a lovely person with a delightful disposition and I was knocked for a loop. After two years I had recovered a little and married Maria, my second wife; she also had a fine disposition and we had 40 years together - she died in 1993 of heart failure. I have been very lucky with my wives.
In 1953 I was granted my naturalization papers and the same year, after running the gauntlet of grades, I became a grade A parts inspector at Sperry's, making some kind of record in speed of promotion. We were then living in Glen Cove, L.I.
The Stellafane Conventions had been suspended during W.W. II but in 1954 they were resurrected; so far as I remember about 400 people attended the early meetings - nothing like the crowds who attend nowadays and maybe more pleasant because of it. In 1955 a hurricane descended on Connecticut and all roads going north from Hartford were flooded, so I was unable to get through.
1956 was a rather peculiar meeting in that the afternoon session under the marquee consisted of a board of "experts" (Aunt Sallies) who were to answer to the best of their ability all questions on telescope making. For some reason I was invited to be on the board and was detailed to answer questions on Maksutov telescopes. I was a little surprised at the interest shown and a hand count showed 35 people interested in making one; I volunteered to do the dog work in forming a Maksutov Club.
On returning to Long Island I sent round a circular letter to the 35 and also to other TNs whom I thought might be interested in buying corrector blanks in a bulk order and so saving a lot of money. I eventually got 69 serious participants; 11 1/2" diameter was decided on as this would accommodate the small spread of the light path if a 12 1/2" mirror blank was used and would provide a very powerful telescope. After contacting several reliable glass manufacturers, I chose Haywards Scientific Glass Corp. as giving the best price for the massive blanks (1 3/8" thick of BSC-2 glass) and sent in an order for 75 blanks.
This was a very good choice as I have had no complaints at all though all the blanks have been sold and a large number of these large Maksutovs have been completed.
With regard to the Maksutov Club, I decided that a lot of information appeared to be required on how to go about building them so I began the Maksutov Club Circulars and in order to save costs bought myself a duplicator from Sears Roebuck; membership, in the Club would consist of buying one of the blanks and subscribing to the Circulars - no other membership fees. Cost of the blanks was $75.50 and the Circulars were to be published six times a year for a subscription of $5 at the beginning, so far as I remember. This was a good deal and I ran the Circulars for 20 years until I retired and moved to England.
It soon appeared that all aspects of telescope making were grist to the Maksutov Mill and I appealed for contributions from all and sundry. Leading telescope makers, amateur and professional, have been very kind to me and I have rarely been pushed for material to put in the Circulars. In addition, Albert Ingalls died some time after publication of ATM III and there was room for another publication - telescope making is an on-going pursuit and new ideas are continually surfacing which would be a pity to deny to other TNs.
The early Circulars were almost entirely concerned with Maksutov telescopes (as was to be expected) but as time went on the subject matter broadened to include almost every aspect of telescope making - such matters as curve generating, testing, testers and a host of other matters. I came across many subjects that had been invented previously but, in my opinion, had not been sufficiently published and so were not readily available to amateurs. These were published in the Circulars (with the agreement of the original publishers) and include such matters as the caustic test, the Gaviola test for convex surfaces, interferometers, improved Foucault testers, spherometers etc. etc. By the 70s the Circulars contained almost as much information as the A.T.Ms (though more "state of the art") and access to such a wealth of information was becoming clumsy so I started playing with the idea of collecting the best of the Circulars into book form and finding a publisher - but I am getting ahead of myself.
In 1966 labour in Long Island was going through a bad period, it was highly skilled but expensive and the major firms (Grumman, Republic, Sperry and others) began to open up branches in places such as Arizona. Sperry began laying off the Long Island work force and eventually they reached my seniority (then 16 years) on a Wednesday. I took a sick day on Thursday and went round to the Kollsman Instrument Co. and filled out an application form. To my surprise the Personnel Manager came out and asked me whether I ran an amateur magazine on telescope making. I said yes and he said he had a job for me, that of optical technician at 30c an hour more than I was getting at Sperry's. I told him that I could begin the following Monday.
On Friday I went to Sperry's expecting to be processed but my foreman told me that they had changed their minds and were not going to lay me off. I said, "You can't do this to me, you told me you were going to lay me off, I have got myself a better job, lay me off!" I went to the personnel dept. where they tried to give me a parting bonus, but my seniority was sufficient for a pension and I insisted on this, rather to their disgust.
I went to Kollsmans and was posted to the "incoming" department; I passed my probationary period without any bother and it soon appeared that I knew more about optics than the average technician. Shortly later I was sent to another department for some reason I don't remember where I saw a 40" beryllium mirror, which was being figured (this was a forerunner to the Hubble telescope). It had been cast with a raised ring at the back for mounting purposes - I remarked to the engineer in charge that they would have trouble with this as there would be a depressed zone on the mirror surface which would be difficult to eliminate. He was impressed and said that I obviously knew what I was talking about as they were having exactly that trouble, would I be interested in transferring to his department as an associate engineer. The answer was naturally, yes.
I went back to "incoming" but my foreman said that he did not want to stand in my way but that he had to have a replacement for me. Optical technicians are at the top of the labor grades and are far and few between so I waited - and waited. Meanwhile I had answered an advert. by Indiana University for an observatory engineer; I took a weekend and went out to Bloomington Ind. to see and be seen - the professor who met me turned out to be a subscriber to the Circulars and I asked for a salary a little larger than I would have got as an associate engineer at Kollsmans. After some haggling this was agreed, and the job was mine - the University agreed to pay for the transport of my now considerable workshop to be added to the astronomical workshop but which would still belong to me.
I went out to Bloomington at the beginning of January, began the job and got a house, my wife followed me a month later with our bits and pieces, having hired a firm to pack the workshop. I had the idea that an academic job would be very pleasant, without the backbiting inherent in the commercial world - I was wrong, my immediate boss thought I knew nothing as I did not have PhD after my name so I never hit it off with him and found that the backbiting went on just the same if not worse. I was never very happy at Indiana University but I stuck it out for ten years until I got a pension.
I attended Stellafane regularly every year and became one of the regular judges for the competitions. My greatest boast is that I was twice seIected as M.C. at the meetings. As time went on more and more Maksutovs appeared in the competitions, more often than not taking prizes.
In or about 1958 I received a letter from a Dr. Baar in Rome N.Y. He asked me a number of questions about Maksutovs which I answered to the best of my ability but I warned him that a Maksutov was too difficult for a beginner and he would do well to make a Newtonian or two before tackling one. He replied to me that he had already made a Mak and would exhibit it at the next Stellafane. So far as I remember, it ran off with the second prize for mechanical excellence and the first prize for optics. I have since been more circumspect with my remarks. Doc Baar has since made six or more Maksutovs - more than anyone else I know - most of them have run off with prizes at Stellafane. He is a superb machinist and is now one of my best friends; we correspond regularly and he has visited me in England several times and I always stay with him when I visit the States (now less often than I would wish - I have got old).
At Indiana University I was in charge of their three observatories the Goethe-Link Observatory with a 36" interrupted Cassegrain reflector, a 5" Zeiss apochromat and the backup instruments - the Forest Observatory with a 16" reflector - and the campus observatory with 12" Brashear refractor. These kept me pretty busy most of the time, what with upkeep of the telescopes and making accessory instruments as required. Life would have been ideal if I had had a better boss.
I have only made one Maksutov but have not exhibited it as it would not have been in keeping with my judging activities at Stellafane. This has not interfered with designs and 12 different Mak designs have appeared in the Circulars, the work of amateurs and professionals, to whom I am very grateful; in addition there have appeared designs for tilted optics telescopes, the Yolo and Solano reflectors (A.S. Leonard), specrohelioscopes (sic) (F.N. Veio), interferometers and other designs too numerous to mention. They all appear in the book "Advanced Telescope Making Techniques." In fact the contents of the Circulars became so wide ranging that it was difficult to make them easily accessible by subject. In 1973 or thereabouts I began to collect the best of the Circulars into book form. The Circulars by this time amounted to about 1500 close typewritten pages and prune how I may, it was impossible to get below 600 pages or so; this would have resulted in a very large and unwieldy book so I decided to split it into two volumes which I entitled "Optics" and "Mechanical". All this editing, in addition to keeping the Circulars going, took a lot of time but I had got it all into satisfactory form by 1975. Next came the job of finding a publisher but eventually Perry Remaklus of Willman-Bell Inc. agreed to publish it in paperback and a very good job he has made of it (it is now available also in hardback).
In 1977 I had served in I.U. for ten years - sufficient for a pension - and retired as soon as the ten years was up as I had never been very happy at the university. My wife wanted to retire in England and although I had my doubts about this I decided to keep her happy, so we sold our house, packed up and moved over to Cornwall in England where I had found a house during a visit (this was one of the worst decisions I have ever made as the U.S.A. is an infinitely better place to live).
Running the Circulars from England would have been very expensive and unsatisfactory so I arranged for them to be taken over by a leading club - this was not successful (probably they were not able to find a member who was willing to put the amount of work into the project) and I don't think that any numbers were published after I gave it up. The Maksutov Club collapsed, this was unfortunate but placed as I was then, I could not do anything about it - after all, people have to retire some time and I was beginning to run out of steam, it was time for someone younger to take over.
The book is still on Willman-Bell's list and has sold a considerable number due to their excellent handling of it. 1975 was early in the time of computers, they were expensive and rather primitive excluding the main line computers which were priced for universities and other large concerns. Private people had to be content with calculators so I finished off the Optical section of the book with a number of programs for programmable calculators - these now seem to be rather elementary but could be useful for those who are not computer gurus. The Mechanical volume deals with all aspects of telescope making that did not fit too well into the Optical volume. Many subjects deal with the amateur's workshop and accessories for testing. One of the objections in my mind to the A.T.Ms is that they have not been edited to any particular plan and so reference to any particular subject is frequently difficult; Ingalls once told me that this was deliberate and necessitated knowledge of the books almost by heart - this may be all very well, but wastes a lot of time if the books are to be regarded as reference books. I have tried to avoid this and have arranged the A.T.M.Ts to the best of my ability in an order where the reference is to be expected - not an easy task considering the variety of he information in the contents. At any rate, the A.T.M.Ts are now the remnant of the Maksutov Club which is rapidly becoming part of the history of telescope making.
When I got to England in 1977, I found that there was little interest in telescope making as such and I no longer had the get-up-and-go to form a club, so I became inactive in telescope making except that I joined John Gregory's club to make an 8" 2-element apochromat refractor. I have got so far as to polishing the elements but unfortunately I had a couple of operations for incipient cataracts and my eyesight is no longer good enough for testing although I have one of Ralph Dakin's sophisticated Foucault testers and a caustic tester. The apochromat is now in the doldrums and although my eyesight is improving, it a slow process and I don't know whether I shall ever be able to finish it. Since I have a pretty good workshop, I turned most of my attention to model making.
I still have a fairly large correspondence in telescope making and know that it is still far more widespread than in England although with the advent of Dobsonians there is perhaps less activity in the more sophisticated telescopes. This is a pity because the more advanced amateurs have potential of adding considerably to the activites of the professionals. After all, many of the professionals in the past began their careers as amateurs.
Now that computers are within the budgets of most of us, the boring part of telescope designing has largely been eliminated and those of us who are computer gurus have a much easier time of it than in the past. Amateurs may still take their place in the forefront of telescope designing.
Schmidt telescopes are very difficult to manufacture owing the (sic) the 4th order curve on the corrector. This is done away with in Maksutovs as they can be made with only spherical curves on the corrector (although a "touch up" on one of the curves will improve performance) - the touch up can be done with autocollimation so no special skill is required in making one and there is no doubt that a catadioptric is better than an ordinary reflector - it has a wider field and for a given size has better resolution. Maybe Maksutovs will still appear in the Stellafane competitions and, I hope, run away with some of the prizes.
Dr. Ferdinand Baar, a medical doctor from Rome New York, had an intense interest in photography. One day he saw a photograph of the moon taken with a Questar telescope and thought that would be an interesting thing to do. But after discovering the cost of the Questar was over one thousand dollars he changed his mind and begun to wonder if he could make such a telescope. Later he read John Gregory's article in the March, 1957 Sky and Telescope describing his new design for a Cassegrain-Maksutov telescope. "I thought I understood it, so I went ahead and got some surface material and surface glass from Edmund Scientific to practice with. And it was very very nice and pleasant to glide one piece of glass across the other. And within moments I was so entranced by doing it that it slipped out of my hands and fell to the ground and broke. That was my first lesson."7 He skipped his second lesson. He would not enter the field of amateur telescope making by the conventional route of first making one or two parabolic mirrors for Newtonian telescopes as advocated by Allan Mackintosh. He would start with the optics for a 4-inch Maksutov, at the age of forty five.
As a matter of fact on the subject of John Gregory, two years ago when we were on a cruise, John Gregory was there, he had just remarried, his wife had passed away, and I realized at that moment that this man had turned my life entirely around. Before that I would do everything but nothing purposefully. Nothing that gave me the satisfaction of grinding glass. I grind by hand, I don’t grind by machine. I got so entranced with that that now I’ve got a cellar that has a lathe, first I started with a small lathe, now I’ve got a 12-inch lathe, 12-inch swing, all the things that become necessary if you are doing your own work. As I tell my wife, "don’t ever worry about it, you know where I am, I’m down in the cellar, you know who I’m with, I’m alone. If you hear me talking I’m cussing myself out for doing something stupid."7
All told, Dr. Baar made four Maksutov-Cassegrains, starting with the 4-inch. Then came an 8-inch F/15 which won second place for optical performance at the 1967 Stellafane convention, and finally two 11¼-inch F/15 designs, the first winning two first awards at the 1969 Stellafane convention, one for optical and one for mechanical excellence. Each one took about two years to complete. Dr. Baar's words from a taped interview follow:
Now you can talk about the kids having a high on dope and stuff, I have never experienced a high like taking double first, the reason being is I wasn’t entering it to win an award I was entering it for judgment. I mean this is what I think I’m seeing, I think its good, as far as I know by my testing and my numbers it’s good, but how good I don’t know. Like the Olympic light bearer, I couldn’t get home fast enough to show my wife what happened.
I donated this (the first 11-inch) to Hamilton College and they asked why are you doing this? And I said because if I don’t get it out of the house, get it out of the back yard I’ll never build another one.
And the business of grinding, even a 12 inch disc or a 11½ inch lens to exact dimensions it’s almost a pleasure it’s not work. When everything is right it’s as smooth as glass, it just flows.
At one point I wasn’t certain whether or not I had a slight hole in the center or a slight hill in the center. Most of my work was done with Ronchi and I also use the Foucault for counter testing as well, couldn’t make it out. It took exactly six strokes, gentle strokes to wipe out. It must have been a wavelength of glass or less. But to know where to do it and how to do it that’s another thing. And this I find very, very appealing, that two hands can do this.
I’ve been hooked by it for years. I find it entrancing, more than I find using it. Now John Gregory, his kicks are from designing. My kicks are from making. Somebody else’s kicks are from using. To paraphrase the old Roman phrase, all Gaul is divided into three parts, astronomy is divided into three parts. Then the design, then the make, and then the use. That’s it.
You want a blunder? Here’s a blunder. I had the 8-inch telescope with the irrigation tubing, aluminum irrigation tubing, and not for window dressing but I thought of insulating it, bringing it up here to Stellafane and just let it sit out in the hot sun it’s going to get hot on the inside by the insulation, I used gasket cork and put that inside. It’s a very very good idea gone wrong because now the heat that is absorbed by the mirror can not escape when things cool off and you have a little will of the wisp floating in there all the time. The cold air coming down against the glass of the lens and then the lens transferring the cold down to the mirror below which is much bigger in weight and density than the lens so it’s going to be much slower to dissipate the heat than it is to accumulate it. I found out about it by a very very simple experiment. I had put three air holes in the back and I blew into one of them like a puff of smoke. And it disappeared. I got a small squirrel cage fan and put it on the back, and you just keep blowing the air in. Once it cooled down so the temperatures were equal, between the inside and outside it was perfect.
Back me up a bit. How and when did you get connected with the Mak club? After you got into your first?
After I finished the first one. You got my letter. Then I approached Mac. about applying to the club, because it was my idea that you had to build one or be building one in order to apply. Now you can understand why his letter reads as it does. (You don’t build a Mak for your first telescope.) But nobody told me I shouldn’t admit it.
I didn’t. I started from what was there. I made my own tools out of plaster, not out of plaster, but out of, oh, it’s a very dense type of plaster, the name will come to me.
To make a Mak meniscus it’s a very steep curve. Did you grind those out by hand?
Oh yes. I started with thick glass but there was a curvature there. That curvature was thick enough and the whole piece of glass was thick enough so you could have a whole series of Maksutovs you could make in that size.
Did you find that out while you were making your first Mak did you say?
Second one. I wanted to learn more about what’s going on and frankly I enjoy the Foucault, not the Foucault, (The Ronchi?) the Ronchi test much better, much more reliable if you do it right. Because the Foucault test can be warped by body English mental body English. (You can fool yourself into seeing what you want.) There’s so much flare and glare. You’re not looking for ______, maybe it isn’t there, well maybe that spot isn’t there and you kid yourself, and how bright is that spot as compared to the hole on the opposite side. Is that as bright as this is dark? And it doesn’t tell you anything. But if you take the Ronchi test and you set it up, you have to make your own jigs with a floating micro head, horizontal and vertical, you can make those lines move backwards and forwards into focus into the focal plane and if you do it carefully enough you will see the lines start to turn and go in the opposite direction that’s the right turning and you go past the focal plane. So you can innumerate your focal plane very very carefully and as it goes back then the lines go through it. It’s like photographing a picket fence as you come up to it and or come back from it. Mac and I have fights on this. He doesn’t trust it because when you use a Ronchi it’s hard to tell on the tips is it a turned edge? The line comes up and you’ve got a little lip, and the line seems to terminate into a little cup, and I keep telling him it is simple, just reverse it. Because if it is a turned edge the sign will be reversed in the opposite direction, when you go past the focal plane.
Now you go in and out of focus and they should reverse themselves.
If they reverse themselves its a turned edge. If they don’t reverse themselves and you still have this semi-silhouette that might be interpreted as a turned edge then it isn’t a turned edge. (Ya, I see what you mean.) And the other thing is, anything over 5 lines 6 lines forget there’s no accuracy. What you look for is, is there any wobble or any wiggle as those lines come toward you, you know toward the focal plane, and beyond and then start to dissipate into multiples again on the other side and that’s the test. That’s what I used to test my stuff, and when I take it out of the basement where there’s no temperature differentials, a pretty uniform temperature, there’s no problem.
That’s true. There’s another project waiting. This is like a big garbage can in dimension.
Was this the 11 inch?
Yes, so the mirror is twelve. (Your first 11 inch?) That was my first 11-inch. And I figured out all the different ways to approach it. And you learn to do these things, and as I say, by having the push pull screws fore and aft I could make my slight adjustments so that I was collimated perfectly, again that’s where the stars come in. If you learn what to look for you can tell if your scope is out of collimation.
What can you tell me about Mac? About how you got into the Mak club?
Well, I sent in my money and I started to receive notices. I said, my God I had missed all of this information, I said how much will it be to get all of the back issues? He sent me all the back issues and I don’t think I got a real nights sleep for almost a week, going through those things. That’s how he did it, in other words, insight into the way other people think.
I have mentored any number of people by letter. I have done it by phone, never having met them, never having seen them. The weirdest one is from a fellow from Prescott Arizona, he had been bugging Mac he was trying to make a 13 incher, I don’t know where he got the glass from, and he was getting into all sorts of trouble. So Mac spooked him onto me, and I get this long distance two hour phone call and I said the first thing we have to do is decide on terminology, this is what these words mean to me and try and get the concept across. And I said the best thing I can think of is that you make a drawing of the condition of your setup, he used a collimated setup, of what you see. He was a good draftsman and I took one look at it, he was using a grinding machine, he was using too much weight, he was scouring the glass, he wasn’t polishing the glass, he was scouring the glass. So I wrote and told him to try using less weight. And he tried and it didn’t seem to do much but I said take off more weight and little by little by little the thing took shape. I had never met the man.
And now there’s a sad part of the story. He finished it and about two or three months later his wife sent me a letter saying he had died, he had pancreatic cancer which is fast, six eight weeks and you’re gone. And she wanted to know what to do with all the gear so I said she should get in touch with the local club and see what arrangements she could work out. The strange thing is I never met the man but he finished his Mak and was happy.7
Prior Chapter: Stellafane Decline and Renaissance 1937 - 1989
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