Stellafane 2001

by Bob Midiri

Leaving on Friday morning August 17th, fellow DVAA members Vince Scheetz, Barry Johnson, and myself embarked on what has becoming our annual trip to the Green Mountains of Vermont, destination Springfield, the home of STELLAFANE. This was going to be a very special convention, since three members of our Astronomy club's Telescope Making class were entering telescopes. Dennis Galvin's 10" F5.6 , Marilyn Michalski's 10" F6.5, and my 12.5" F6.7 - all DOB's. In stark contrast to last years prolonged drought on the east coast which devastated the many trees we witnessed during that years trip, this season rain was much more plentiful, giving renewed life to the compromised forestry. Arriving by early afternoon, the first item on my agenda was to register at the Hartness House, a gift from my wife for my birthday. The Sun was shinning on Breezy Hill as I entered the observing field, adjacent to the McGregor Observatory which houses the Schupmann Telescope, and hopes were high for some serious star gazing that evening. Though Stellafane may be perceived as a star party, it has been, and still is, intended to be a convention of telescope makers. After all, since the start of this convention in the early 20's, the "Heart and Soul" of Stellafane has been the good spirited telescope competition amongst us amateurs! The Springfield Telescope Makers are always striving to make the convention ever better. Last year they started employing "online" telescope competition entries, which saves an enormous amount of time at the convention, and this year added an additional night for optical judging. This was an enormous boost to us mirror makers, especially since each of the last 2 years the optical judging, usually done on Saturday nights, have been a complete washout. At the observing field as usual, scopes were set up for people to admire, and to do some solar observing. I first ran into John Vogt from New York, who built a most wonderful 32" dob, and had a Celestron Nextsar 80 with a Coronado solar filter. The solar flares were quite evident and crisp through that little scope. I then ran into Barry Peckham of Lite Box fame from Hawaii, who was visiting family in the New England area, and making another trip to Stellafane. Barry is one heck of a guy, in fact while here, he made a 7 hour trip down to S.E Pa. to give a talk at our clubs monthly meeting. Unfortunately for me, my work schedule prohibited me from attending, but we got to spend a lot of time at Stellafane together, since he roomed with me at the Hartness House. If you have never seen one of Barry's Lite box scopes, you are missing a treat. Starting from the assembly of the cage, which only weighs 5 lbs with the focuser, to final collimation of this 12.5 inch truss tube dobsonian, you can see the carefully thought out design of this very lite-weight scope. Barry uses 12 mm Baltic Birch, glued and screwed, with corner bracing, and finished with a textured plastic laminate made by wilsonart called "Pearl Sand". Also he uses "Ebony Star" for all his bearings along with Teflon. Other color schemes are available, The 3 accent color schemes which in addition to the speckle black (ebony star) and speckle white (pearl sand) are: Burgundy with Wilsonart "Scopia" laminate (mottled burgundy) Navy Blue with some burgundy (mirror box handles and ground board) and Wilsonart "Artesia" laminate (mottled blue), Hunter Green with some burgundy and a mottled burgundy laminate called Wilsonart "Heather Legacy". He uses 7/8" diameter truss poles of T-6, 6061 aluminum and an ultra light and compact aluminum truss clamp system, further reducing the total weight. The poles are attached on the mirror box, by one piece of horizontal C-channel which presses 2 poles into 2 pieces of L-angle mounted to the side of the mirror box. There are stops at the bottom of the L-angle pieces. The C-channel is held by a center bolt, a spring tensioner and horizontal stabilizers. The poles connect to the cage by using a system nearly identical to the Tectron system: 4 pieces of L-angle, 8 bolts and 8 knobs. It takes up less room and weighs less than any other system Barry has seen. The scope components break down and fit snug within each other for easy transport. He also uses JMI DX3 focusers along with Novak or Protostar hardware. He also is a proponent of the virtual spring counterweight system, which reduces the size of the mirror box. The whole goal is striving for lightweight without compromising stability. So how lite weight is this scope, well its 55 lbs without the primary (70 lbs with). Just before heading over to the Big Tent, there was a beautiful 22" F4 Starmaster with a mirror by the Great One (no not Wayne Gretsky, but Carl Zambuto)! Tony Peryra, the owner of this fine scope has a fully goto scope with a nice clutch less drive system. At present he has a SkyCommander attached in which he enters the object he wants to observe, then he goes to another hand paddle to initiate the scopes goto function. His goal is to make this a one step process, and cordless at that. He also is working on a remote control for collimation of the primary mirror, while at the eyepiece end. I sure hope Tony has all these features by next years Stellafane! In addition to Tony's 24" Starmaster, a 36" and a 25" Obsession were set up on the Observing Field. After seeing the size of that 36" scope (don't know how you do it Tom!) I think I will be quite happy to end my aperture fever with the 22.6" mirror I have just finished grinding!

At the Big Tent, the mirror grinding demonstrations were in progress! It is here that many first time glass pushers get the opportunity to ask questions and get hands on experience at mirror grinding. Josh Morrman a 13 year old from Fredericksburg, Virginia, was enthusiastically doing some real serious glass pushing. He was working on grinding a former 16" tool, 3 inches thick, perfectly flat, to then be used to make a mirror!. The way Josh was working, I am sure he reached his goal in no time. Even Howie Glatter was spotted pushing some 8" glass. Along with grinding, there was polishing, lap pouring, and testing demonstrations in progress. Dave Kelly and Scott Milligan are the guys to talk to for information on optical testing. A wealth of knowledge, a lot of encouragement, and inspiration can all be harnessed by the would be future mirror maker at Stellafane! Many other activities are held during the day, from horseshoe pitching contests, astronomy activities for kids at the McGregor Observatory, browsing through the library, or even visiting the Hartness House Museum. The Hartness House Inn built in 1903 was the former home of James Hartness, Governor of Vermont from 1920 to 1922. He was an inventor and astronomer, and in 1910 the Turret Equatorial Telescope was built there. He entertained such well known guests as Charles Lindbergh and Russell Porter. If you have the chance, the museum is a wonderful opportunity to see some of Porters and the early Springfield Telescope Makers workings.

Since Friday night would be set aside for optical judging, an early dinner at a local Chinese restaurant was our next item on the agenda, before that evening. Optical Judging is always done over at the Pink Clubhouse, and since my 12.5"F6.7 dob, along with fellow DVAA member Marilyn Michalski's 10"F6.5 were to be entered, we all made the trip up the hill, past the old Stellafane grounds, to the place where it all started, the Hallow grounds which was once walked by the likes of Russell Porter, Robert Cox, Walter Scott Houston and now Roger Tuthill. Anticipation was building for optical judging that Friday evening since the weather seemed to be cooperating. According to Scott Milligan of the STM (Springfield Telescope Makers), the plan was to have two groups of judges out on the field that night, since there was such a large number of scopes to be judged. After 3 years of no optical judging, a large percentage of the scopes were those returning for this years optical judging. The skies were quite clear, and we got to observe a number of fine DSO's, waiting for the judges, as dew was becoming a big problem! By 1:30 AM, they finally arrived to my scope, and one of the judges, Marianne Arien, told me that half the judging was completed, unfortunately within 30 minutes the skies were totally clouded out, and the rest of the judging had to be canceled , including any chance on Saturday night. Oh well, us mirror makers will have to wait till next year! One suggestion I made was maybe to do artificial star testing during the day, since Stellafane has ball bearing reflectors mounted on some trees on the hill, to act as the artificial stars. Tom Spirock of the STM's said that this may be taken into consideration. Well it was now time to head back to the Hartness House, for some quick zzzz's, since bright and early Saturday morning the swap tables would be buzzing with bargain hunters. As usual, the Stellafane Swap Meet is loaded with great items. I did notice a marked decrease in the number of available mirror making items this year, but eyepieces, telescope making hardware, books, binoculars and telescopes were everywhere. It was also great to see Mrs. Roger Tuthill set up with a lot of the great items we have known to expect from our friend and fellow amateur, Roger Tuthill, who will be sorely missed by us all. Thank you Roger for all you had done for amateur astronomy.

Late Saturday morning is the time Stellafane really shines, the "Heart and Soul" of this convention, the telescope competition! There were a large number of extraordinary scopes this year, unfortunately time and space will not allow justice to every one of those fine scopes. But I hope this representation will give you an idea.

Again, Bob Novak, of Cransberry Township, Pa. has made another awesome telescope. It was only a couple years ago that Bob brought his beautiful 8"Yolo, followed by his 10" F7 truss dob with a rotating OTA. This year Bob brought something real simple, just a 16" Ritchey-Chretien Cassegrain scope. The only thing he made, well, was the whole scope (except for the focuser which he modified to lighten the weight). Its in a word, unbelievable! Lets start with the optics. He made the 16 inch 1.6" thick Pyrex glass into a F-3 Hyperboloid, the 4.25 inch secondary is convex, with a hyperboloid shape which has a magnification factor of 2.5, giving the scope an effective focal ratio of F7.5. A 2.125" flat brings the focus of the instrument out through the middle of the OTA, so the observer can be seated, regardless of where the scope is pointed! Testing of the primary and the concave secondary tool was done using the Ross null test. The Ross lens is a 4.7 inch diameter plano-convex surface of 14 inch focal length. The spacing was determined by using a ray trace program (Beam 4). A Ronchi screen (150 lines/inch) was used to assure proper set up and collimation of the tester. The convex secondary surface was brought to the same radius as the concave tool before figuring was started, verified by using interferometry. After the concave tool was brought to the correct hyperboloid, the convex secondary was brought to same figure by monitoring the fringes. This concave tool was also then re-cycled afterwards to make the primary for his 4.25" F5 Finder scope, which weighs only 4 lbs. All the mirror surfaces are coated with Beral coating. The main tube was fabricated from 3/4 inch aluminum tubing. Round tubing was used for the longitudinal stringers with 3/4" square tubing for the end octagons. The tubes are held together with 1/8" pop rivets via gusset plates. Four aluminum flat panels (.062") are used on the horizontal and vertical surfaces for stiffness. They are also pop-riveted in place. The diagonal panels are 0.032" Kydex plastic and allow easy access to the interior because they are held in place with Velcro. The base is constructed of 1" square aluminum tubing, again secured with gussets and pop-rivets (ALA Eiffel Tower construction). As with the main tube, it is very light and rigid. It weighs only 11 pounds and with the OTA of 59 pounds, the total scope weight is 70 pounds. The trunion bearings, made also from aluminum tubing, was routed out to a semicircular shape. All bearings are ebony star on Teflon. Bob also fabricated the 18 point mirror cell, fitted with an exhaust fan. The scope has very smooth motions in both axis, a real winner, thanks Bob!

Dennis Galvin, from the Philadelphia area, and fellow member of the DVAA had his recently completed 10" F5.6 Dobsonian on display. They say good things come to those who wait, well this is no more truer then in this case. Dennis started the initial planning for this scope back in January of 1995, and it was completed just prior to the convention. This beautifully constructed dob, with its mount adapted from some of Barry Peckham's models, is made out of 3/4" apple ply. The heart of the scope is a full thickness 10"F5.6 Nova Optical mirror. Vince Scheetz, instructor of the DVAA telescope making class, tested this mirror and found it to be one of the best commercial mirrors he had seen. This mirror has an enhanced 96% aluminum coating, while the 1.83" secondary has an endurobright coating, yielding pretty much maximum reflectivity in his optical system. The main mirror is mounted on a 9 point Novak cell, while also using a Novak spider and secondary holder for the flat. Dennis used a white Parks Fiberglass optical tube, with black end rings, giving the scope an almost big brother look to his TeleVue Refractor. This OTA sits in a cradle with two features that set it apart from the more common dobsonian style. Dennis calls this his adjustable balance cradle. Loosening two thumb screws on the top of the cradle, reduces friction on the OTA, so it can be rotated for comfortable observing. There also is a thumb screw on the bottom side of the cradle which places pressure on the cork lined rings for friction. Loosening this thumb screw allows the tube to be moved forward or back making the balance point adjustable, for those heavy Nagler's. The scope itself weighs 84 pounds. His bearings utilize the tried and true materials Teflon and Ebony Star, with a bearing weight pressure of 15 lbs per square inch. This scope moves buttery smooth, it is as good looking as it is to look through it.

The most beautiful crafted scope belonged to Norman Fullum of Hudson, Quebec. His 8" F3.62 Dobsonian was made out of hardwood maple. Norman put a real astronomical twist on the scope. If you look at his rocker side boards, they are cut out to the shape of the constellation Cassiopeia. While the homemade helical focuser made out of maple and aluminum, to the shape of an edge on Galaxy. Norman made the mirror himself, testing with his homemade Foucault Tester, to 1/10th wave. He said that there is some coma, with certain eyepieces, but not enough to degrade the image or warrant him purchasing a coma corrector. The tube is made of 16 pieces of maple cut 5/16" thick by 1 15/16" wide, each cut at a 11.25 degree angle. The planks were laid flat and parallel to each other on top of long strips of masking tape and glued between the joints. Then all at once you pull the tape and join it together to form the tube shape, and let cure. The mount is 1" maple glued, cut with a jigsaw, and sanded with a drill equipped with sanding drums. The finder is made of cherry wood turned on a lathe than pierced with Fostner bits, to make the optical path. The primary cell as well as the secondary are made of maple except for the spider veins which are made of metal. Even his eyepieces and barlow were made of lathe turned maple. The bearings consist of Teflon pads on both axis, with Ebony Star on the ground board, and Melamine tape on Teflon for the side bearings. The maple has a natural stain, with 7 coats of polyurethane, and the finished product has been waxed for maximum protection. Congratulations Norman on this exquisite craftsmanship.

Carl Lancaster of Riverside CT brought his impressive 18"F4.5 Horseshoe split ring with rotatable upper cage. Carl says he is retiring from telescope making, and after seeing how much time and effort put into this scope I can see why! The bottom tube assembly was made with a 32 sided maple barrel, and sanded round. The Galaxy Top Gun 18" F4.5 mirror sits in his homemade 18 point flotation cell. The top rings of the upper cage are made out of Apple Ply. He also made a 2" filter slide for the focuser. All the wires utilized for dew removal of the secondary and primary, are hidden inside the tubing. All the electronics are home brewed, and powered by a 12 volt regulator. He also uses 8192 TIC encoders for his digital setting circles. Carl says this is mostly a visual scope. It is visually nice to look at as well as through it.

Victor Chiarizia of Talcottville, Connecticut, a Glass Blower by trade made his 16"F5.6 dobsonian telescope out of Baltic birch with Bubinga veneer. The framework of the scope was built "like a boat" using ribbing, which was wrapped with 1/8" marine mahogany, marine expoxied, then covered with the Bubinka veneer. He machined the focuser using Matt Marulla's design from the ATM page. The upper cage is rotatable, but may need some tweaking for collimation. The altitude bearings are made from machined aluminum with twin needle bearings in split mahogany blocks. All the machining and drive units were done by Victor, based on Mel Bartels Alt/Az system. The 16" mirror sits on top of 1/8" foam, with 3/4" Baltic birch as its bottom support. Well if this wasn't special enough, the mirror is a cellular design, hand cast by Victor himself. The Borosilicate is liquefied in a fusing oven at over 2000 degrees Fahrenheit., in a mold. The mold is 2.5 inches thick, and the face plate of the mirror is 5/8" thick. This 16 inch mirror weighs only 17 pounds. He also is experimenting with larger sizes, to see how well they hold up. This is very exciting, and we hope that he can perfect his hand cast Borosilicate cellular mirror blank design. He also ground, polished, and figured the mirrorwith Dick Parkerbeing his mirror making mentor.

I also have to mention a very unusual telescope brought by "SanDiego"Bob May of San Marcos California. This scope has a small 4.25 inch objective, but is anything but small. Its focal length is 200 inches. It is a single lens design, copied from the era prior to the development of the achromatic lens. The optical tube is made of a beautiful natural lacquered Cherry Wood . The mount is of Herschelian design. The OTA breaks down into 4 section for transport, as does the mounting system. If you look at the scope from a far, it reminds you of how a projection screen would appear prior to opening. Even Bobs car is a classic, made in the early 50's. He uses 3" eyepieces of Huygens design. The telescope sections fit nicely inside the old truck, in which Bob modified to carry this most unusual telescope.

Another really impressive scope was an 18" F 4.2 Fork Mount Truss by Albert Maloni of Merchantville, New Jersey. To make the 18" F 4.2 mirror, Al built an Elgin grinding machine for all the grinding and polishing. His mentor was John Hall of Pegasus optics, one of the best mirror makers around. It took Al 14 months to grind, polish, and figure the 1.6" thick mirror. The top cage and bucket are from a JMI NGT. The trusses are expandable paint sticks purchased at a local Home Depot home improvement store. Al designed the fork mounted assembly, made a model out of cardboard, drew the plans to scale, and sent the plans to a machine shop for fabrication. The scope has a Sky Commander DSC, and Sky Tracker GOTO. Vic of Sky Command made modifications to do tracking for CCD photography.

After checking out the beautifully crafted homemade scopes, it was back down to the big tent area where the afternoon talks were underway. The unflappable John Dobson gave a nice question and answer session on his most favorite subject (no not mirror making) cosmology. There also was a very interesting talk on optimizing refractive surgery to benefit the amateur astronomer, by Barry Santini of Seaford, New York. Since optical judging was scheduled to try its hand battling mother nature again, it was time for a quick bite to eat, then head back up the hill to set up the scopes. Luckily I was running late, cause it started to rain for 20 minutes as I arrived. While waiting for the sky to clear, and the sun to dry the field, my friend Harry Orlind, discovered a very nice hiking path behind the telescope field on Breezy Hill. He also discovered an old shack that had the most awesome view of the valley and hills below. I have to wonder if this was not an area that Russell Porter had to frequent, we were all awestruck by the view! Unfortunately optical judging again would be canceled by 10 PM.

Though I could not make the evening Keynote talk, I heard that Derrick Pitts, planetarium director in Philadelphia, gave a talk about popularizing astronomy through live radio programs. Our club the DVAA has participated in a number of these programs with Derrick. Now becoming a very popular sport at Stellafane is the annual prayer session just prior to the door prizes. All are perspective hopefuls for Al Naglers most generous donation, a basket of Naglers, Radians, Panoptics as the top door prizes at Stellafane. Unfortunately again, I did not come close. Will pray harder next year!

As usual this was another wonderfully run Stellafane convention by the Springfield Telescope Makers. We owe a great deal to them for making this the weekend we long for, the whole year. Their expertise, and patience will long be remembered by all who attend. I personally want to thank Scott Milligan, Tom Spirock, Dave Kelly, Maryanne Arien, and all the STM's who put their blood, sweat, and tears in making this the ultimate amateur experience in the world. Hope to see all at next years convention, on August 9th and 10th.

Bob Midiri
309 Baltusrol Dr.
Coatesville, Pa. 19320

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