- Celestron PowerSeeker 70AZ Telescope ($10 Scope)
- Orion EQ-26 Mount Review
- Review of Explore Scientific First Light 8
- Rebuilding my CGE Pro
- COUNTING SUNSPOTS WITH A $10 OPTICAL TUBE ASSEMBLY
- Hubble Optics 14 inch Dobsonian - Part 2: The SiTech GoTo system
- iStar Optical’s Phantom FCL 140-6.5 review
- Who’s Afraid of a Phantom: Istar Phantom 140mm F/6.5, that is?
- SHARPSTAR 94EDPH APOCHROMATIC REFRACTOR
- My Losmandy G11T review
- FIELD TEST: THE NOH CT-20 ALT-AZ MOUNT
- SkyTee-2 Alt/Az Mount Review
- SharpStar Askar ACL200 200-mm f/4 astrographic telephoto lens
- A review of the Unistellar EVscope
- Astrotrac 360 tracking platform – first impression
CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.
Teeter #66 - A 14.5" Truss Dobsonian Telescope Review
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Teeter #66 – A 14.5” Truss Dobsonian Telescope Review
By Jim Cole
This review is broken down into the following parts so you can skip the stuff you’re not interested in:
- My Amateur Astronomy Background (The life, death and rebirth of astronomy in my life)
- Due Diligence and Placing the Order
- Chosen Options for my Build
- The Build
- Delivery and Unpacking
- Assembly of the Telescope
- First Light in Flagstaff
- Six Nights at the Texas Star Party
- Summary and Conclusions
MY AMATEUR ASTRONOMY BACKGROUND
Skip this part if you want to get right to the fun stuff. It’s kind of long and will bore most of you.
I started my amateur astronomy career in south Florida in June of 1989 with a 60mm department store refractor that, like a lot of folks, I could never figure out. Within a week I had returned the 60mm for a red 4.5” Tasco Newtonian that sufficed to light my fire. I was hooked! I joined the local Fort Pierce astronomy club and really enjoyed myself. It was a small group of 20-30 folks with only about 4 or 5 of us being serious observers. Within 2 years I found myself the president of the club, an office I held for 2 years until I moved away in late 1994.
In June, 1990 after owning the Tasco for only a year, I was presented with the most amazing birthday gift I had ever received, a shiny blue 14.5” f/4.5 dobsonian telescope made by a fellow down in Jupiter, Florida named Andy Johnson. It held a mirror by a highly regarded mirror maker named Richard Fagan. People in my club were stunned by the views as the largest telescope in the club up until then had been an 8” Meade SCT. It certainly blew away my Tasco. The Tasco was sold to a fellow club member for $50. I bought a few TeleVue eyepieces over the next couple of years including 2 of the first few Naglers that were available, the 9 and the 16. That scope was out to the dark sky site about 12 miles from my house twice a month, weather permitting, and in my front yard or my friend Walt’s yard a couple more times a month. It made it to 2 Winter Star Parties in the Florida Keys where I first met Al Nagler and Tippy D’Auria. I logged 380 objects with that fabulous scope in it’s first 2 ½ years. I was addicted to the night sky.
At the end of 1994 I moved to Chicago, and living in a 3rd floor walk-up in the city, my telescope time was reduced to being an occasional sidewalk astronomer, enticing neighbors to peer at the planets or the moon through the big scope and one special night asking people on the street to look up at comet Hale-Bopp that was a spectacular sight, even from the light polluted streets of Chicago. I should have linked up with a local astronomy club, but I didn’t find the energy. I was traveling a lot for my new job as a software consultant, and I began skydiving with my wife on almost every free weekend. I took the scope to our skydiving drop zone a couple of times and thrilled my fellow skydivers. However, I logged no new objects after leaving Florida. The fire was starting to go out.
In April, 1999, my wife and I quit our jobs and sold our condo in Chicago and planned on traveling around the US for about 9 months. I bought the then, newly announced, TV-85 specifically for that trip as we were traveling with a Grand Cherokee and small camping trailer. The 14.5 went into storage. We ended up spending a year in Anchorage (it was too beautiful to leave when the snow started) and did very little observing of anything but northern lights because of the cold in the winter and the lack of dark in the summer. Tough place to be an astronomer, but spectacular for everything else! The fire was mostly smoke now.
In 2001 we stopped traveling in Flagstaff, AZ and for some reason, the 14.5 although released from storage, made only a twenty or so trips outside under the stars in the next several years. One time in my carelessness, I left the scope set up outside on my patio for two weeks under an oversized yellow plastic garbage bag. I should have been charged with telescope abuse. It was rained on several times and one time a wind gust spun the scope around and knocked it over, crashing the UTA into our patio table, cracking its wooden shell and splitting the now aging wood in the mirror box where the trusses attached. That was in 2007 and the scope was disassembled and put away, never to see the Milky Way again. The Jupiter telescope was 17 years old. The fire was down to a couple of fast cooling embers.
By the fall of 2009 my observing time was down to a couple of hours every few months, through no one’s fault but my own. It’s most surprising that I couldn’t get my original enthusiasm back even after moving to Flagstaff, AZ the first International Dark Sky City in the world. My back yard is Bortle 3 for Pete’s sake, with Class One skies within 30 minutes! Go figure. My 14.5” Jupiter dob was a wreck and my TV-85 just didn’t seem to offer the excitement that my big dob once did. It was killing me that I had lost the bug. My wife knew it, too! She knew, deep down, that a part of me was missing.
After spending a few nights outside in September 2009 observing with my wife with our little refractor, we decided that I should sell the TV-85 and apply the money to a new structure for my still excellent 14.5” mirror. I knew that my wife missed looking through the big dob as well. The last dying ember erupted into flame.
DUE DILIGENCE AND PLACING THE ORDER
Now having been away from the amateur astronomy community and completely out of the technology loop for many years, I knew it was going to be tough to figure out where to go to get a new dob structure built. I began searching the internet for truss dob builders and began reading everything I could find. I finally stumbled on to a wonderful web site called Cloudy Nights. Ah, salvation.
I read a lot of reviews and at first considered a “finish it myself” kit for economic reasons. I’m not a wood finisher and my garage space is limited, winter was on the way and I just didn’t want to.
There were only 2 or 3 manufacturers who would allow you to supply your own mirror. Some other makers simply didn’t want any mirror that didn’t come from their chosen supplier to contaminate their masterpiece. I guess I understand that, but it didn’t help me. One of the companies who picked my interest the most was Teeter Telescopes. I mean, just look at them!. After studying the Teeter web site for a few days, looking up the only review I could find on CN, discovering some definite technology advantages with his designs and knowing that he would make a completely custom scope if I wanted using my mirror, I gave Rob a call and had a little chat. He was very friendly and helpful and at the end of the call I had pretty much decided to send Rob a deposit. On October 10th I sent him a $100 “good faith” deposit and that got me the last spot on his April 2010 delivery schedule. I was a just a little anxious as I was getting ready to spend about twice what I originally had in mind when I was looking at a kit. I also had never laid eyes on a Teeter Telescope before. The anxiety didn’t last very long though.
A really critical part of my decision to go with Rob is that he would take delivery of my mirror for the final assembly and testing which includes at least two tests of the completed telescope under the night sky. This guarantees that the mirror will perform as well as its figure allows, that the scope is balanced correctly and all electronics are performing correctly. My scope was to be built to balance correctly in a range from an empty focuser all the way up to the weight of a 31 Nagler / Paracorr combination. The optical design was also calculated to allow me to add a set of Denkmeier Binoviewers down the road and not have to deal with focus issues. The Denks will, of course, also require counter weights, but other than that, they should be plug-and-play.
It took me about 10 days to sell the TV-85 and then a check for half of the cost of the telescope was off to Rob with a list of options I wanted on the build. The options list was to change a few times before and during the build process. Rob took them all in stride. A couple of changes occurred after I would read about this or that on the web and call or email to Rob with questions. Replies were almost always the same day, sometimes the next. Rob does have a full time day job and I was a little concerned about that at first, but nothing I read anywhere on line from any of his past 60 or so customers contained one negative comment about Rob, his integrity or his exceptional skills as a telescope maker. Most of the build decisions were made by the end of January.
The waiting had begun.
I also started contacting mirror re-coating companies and decided to send my mirror to Optic Wave Labs in California who would then forward it to Rob in New Jersey after the stripping, basic testing and coating. Cary at OWL was very helpful and very informative when I requested information about procedures and types of coatings. After listening to Cary and reading way too many arguments on CN, I decided on the standard coatings, not because of price, but because of the lack of empirical evidence to support the additional cost of enhanced coatings. Cary himself uses the standard coatings on his personal mirrors, even though he offers enhanced coatings through his own company.
OWL’s turn-around time is only a week or two, so I didn’t need to send the mirror in until the 1st of March which would put it in Rob’s shop by the date he wanted to have it there.
In the mean time, I had James Grigar at Astro Sky Telescopes build me a beautiful wood mirror box with a cherry stain that would be close to the color of the new scope. This box with the mirror inside would go into a second foam lined, double-walled cardboard box that I had special ordered to a specific size for shipping the mirror around the country. The mirror would make two complete trips across the continental US.
CHOSEN OPTIONS FOR MY BUILD
Teeter’s Telescopes web site has changed since I placed my order, with a lot of the options I selected now standard at a higher initial package price. Although the current pricing is different, it is not higher than the old base price with the options added. The new customer doesn’t have to make as many decisions and the new standard builds are complete (less the mirror selection). Rob has built scopes with mirrors from all the premium makers, so it’s the customer’s choice whose mirror to use. There are still several upgrades available for additional fees.
This is what my final order looked like after a few iterations:
- Ultra Limited Edition Structure for a 14.5” f/4.5 Telescope in a Cherry Stain. Mine is #66.
- 3.1” 1/20th Wave Antares Pyrex Secondary (Upgraded to Fused Silica Quartz courtesy of Antares)
- Welded Steel 9-Point Flotation Mirror Cell (Upgraded to an 18-Point Cell courtesy of Rob)
- Glatter Cable Sling (Special request by me and another customer, but now an available upgrade)
- Round, Knurled Primary Collimation Knobs (to replace the T-handles that come on the cell)
- Moonlight Dual-Speed Crayford Focuser (Pick your color)
- Sky Commander Hardware Kit (I’ll be buying the Sky Commander sometime in the future)
- 12v, 7Ah Battery Package with 800mA Float Charger and Wiring Harness
- ProtoStar 4-Vane Secondary Holder with Integrated Dew Control Heater (not currently available)
- Rigel Quik Finder
- StellarVue 9x50 RACI Finder with Mounting Rings (Upgraded to a SV 10x60 courtesy of Rob)
At this point Rob had decided to stop using ProtoStar spiders and go with AstroSystems. He told me that he would substitute the AstroSystems spider, secondary holder and dew heater system for the ProtoStar, but I really liked the more elegant dew heater implementation of the ProtoStar and Rob yielded to my request. I should have listened to him as we’ll see later.
Rob’s CAD drawings for the woodwork went to his mill shop sometime in the middle of December. Rob explains that by laying out the woodwork design himself and then having a professional shop do the ordering of the wood and the cutting, he saves time and effort, saves the expense and space requirements of a full woodworking shop and gets extremely accurate and consistent cuts.
Rob retrieved the Baltic Birch parts from the mill shop in early February and proceeded to sand, stain and clearcoat the pieces. He puts seven coats of super gloss clearcoat on the wood after staining for a strong and beautiful protective finish.
As the build progressed I brought up the following questions with Rob:
- Is there a mechanism to control the fan speed to allowing them to run on a lower speed if necessary during observing? Bottom line, it’s a difficult problem, but Kendrick is working on just such a solution and may be a year or so away. He suggests turning off the fans during observing.
- Can I incorporate a Moonlight Internal Filter Slide into my build? Based on the way Rob designs his UTA along with my requirement for the Denk Binoviewer, the answer was very detailed, but his final answer was “To summarize a long train of thought - the Filter Slide won't work without a number of modifications and extra hardware and almost certainly couldn't be used when using a Binoviewer”. I scratched the idea of the filter slide.
Figure 1. Build in Progress. Stain and 7 coats of clearcoat applied. Truss ring complete.
During the build, the following improvements to Rob’s original design were made at no cost to me:
- He added a switch for the boundary layer fans on all future builds so the user didn’t have to plug and unplug the wires to the controller.
- He decided to increase the size of the altitude bearings on all 14.5-15” structures from 19.5” to 23.5” to better handle changes in weight up at the focuser end of the telescope. Thanks to Ben for the original request on his Teeter.
- He also decided to make the 18-point flotation cell standard on all his 14.5-15” structures to better handle thinner mirrors. My mirror is an older 1.75” thick mirror and I had ordered the 9-Point cell, but Rob thought that someday I may want to upgrade the mirror (we hadn’t got the results back from OWL yet) so he ordered the 18-point cell upgrade for me at his expense.
The telescope just kept getting better and better from order to delivery. Exceptional customer service!
In mid March, Rob received the re-coated mirror from Cary at OWL along with the mirror test results. I was happy to find out that the Strehl Ratio is 94.7 with a P/V wave front of 1/8.5. I knew it was a good mirror, but we didn’t mess with numbers so much back in the early 90s. Cary told me that he thought momentarily about offering me a refigure, but then decided it would be silly and any improvement he could make wouldn’t really be visible at the eyepiece except by exceptional observers on rare exceptional nights. I’m happy knowing that my 20 year old mirror is as good as I remembered.
The final upgrade, courtesy of Rob, was made during final assembly and testing. It turned out my mirror is actually an f/4.4 not an f/4.5. This resulted in Rob having to cut the trusses 1” shorter than planned which caused a loss of a few ounces of weight near the top of the scope. Rob did some quick thinking and decided that the weight could be made up using the larger 10x60 StellarVue finder. It was installed and the balance of the scope was restored to expectations with no increase on my invoice.
Now, I don’t want any future Teeter’s customers to think that Rob will be upgrading their orders willy-nilly for free, but I assume that if he decides there is a better solution to a problem that he wants to make standard on all his builds, and if your scope is in the build process where the new solution can be applied, he will do it. He told me, after deciding to put the 18-point mirror cell on my scope, and I quote, “just consider it part of my pursuit to put my best foot forward”.
I notified Rob on March 9th that I was planning to attend the Texas Star Party in early May if my scope was going to be ready. He replied that he would try his best because he didn’t think there had ever been one of his scopes for the world to see at the TSP. He would like to see that happen.
My scope was originally slated for April delivery. Rob told me in early April that he had three other telescopes that were ordered before mine that he needed to finish up for delivery at NEAF in New York on April 18-19. One or two of these were running late because of supplier issues. He said that he would try to get mine finished and shipped before NEAF, but if not, certainly by the end of April.
When it didn’t look like Rob was going to complete my build before NEAF, I did a little calendar calculation and sent him an email on April 14th letting him know that if he wanted to have the scope to me before I needed to leave for Texas on May 8th, He would have to have the scope delivered to the UPS store for packing by April 30th or better yet by the 29th to allow for any possible delivery snaffus. The thanked me for putting the date in his head (although he was already aware of it) and for “the encouragement”.
Rob returned from NEAF and almost every evening that first week back he had commitments for children’s outreach programs. He spent the next weekend (April 24-25) and Monday night finalizing assembly of my telescope and then we both prayed for two clear nights on Tuesday and Wednesday so he could get the final systems checks done. He even took the time to take the measurements I needed for Bob at Telegizmos to make the cover I needed to have for the TSP. He also installed the new CatsEye HotSpot on my mirror.
Well, Rob worked his butt off (on work nights, too) and the New Jersey weather cooperated (just barely) with the end result that I received an email from Rob on the morning of the 29th to let me know that the scope was in the hands of UPS. Woo-Hoo!
Rob Teeter totally pulled through for me. The TSP was my planned vacation for the year and I could not think of a better way to first light a new telescope than to spend an entire week under the pristine skies of west Texas doing just that. Man, those last two weeks of April were nerve wracking. If Rob’s time had been pinched or the weather hadn’t cooperated for those specific two nights, I would have been very disappointed. As it was, it had rained during the daylight hours on both days and then mostly cleared up after 8pm just when Rob needed it to. I must have done some good things so far this year because my Karma came up aces.
DELIVERY AND UNPACKING
The UPS man showed up on the evening of May 5th. As usual for important deliveries, it was the only night I had something scheduled, so my wife took delivery. I found it funny that I was at a Lowell Observatory volunteers meeting, trading one astronomical adventure for another. It was killing me.
The scope came in 5 boxes. Two fairly large boxes contained the mirror box in one and the rocker box/ground board unit with the UTA nestled inside in the other. The heavy cardboard medium sized box that I had custom made contained my wooden mirror box and mirror and was still in good shape after crossing the continent twice (Arizona → California → New Jersey → Arizona). A tall box contained the wheelbarrow handles and the truss poles in the carry bag by Shrouds by Heather. One smaller box contained all of the accessories to the telescope.
Figure 2. The Teeter arrived in 5 boxes. My cat Sam is inspecting the merchandise. The well traveled mirror box is in the foreground.
The large box containing the rocker box and UTA was pretty crushed on one corner, but the internal packing held up well and no damage was done to the contents, at least on initial inspection. The tall box had a hole ripped open about 7x5” and the zip lock bag containing the four hand bolts for the wheelbarrow handles was ripped open causing the loss of two of the bolts and some light scratches to the finish of the handles. The missing bolts weren’t an issue, since I had planned on leaving the wheelbarrow handles at home for the trip to the TSP and the light scratches didn’t bother me as much as if they had been to the main scope structure. I offered to pay Rob to ship me two replacement bolts since this was a UPS issue, but he insisted that he would send them out Priority Mail at no charge. Thanks Rob! Rob was also going to talk to the UPS Store about the loss as they did not wrap the wheelbarrow handles or poles in bubble wrap before putting them in the box. This would have eliminated the loss of the bolts and prevented the scratches to the handles’ finish.
Figure 3. UPS does their thing. Two hand knobs were lost through the hole via the ripped plastic bag.
Everything else arrived in pristine shape (well, almost, which we’ll address in a little while) which made me very happy since my opinion of UPS has always been a bit weak.
Figure 4. The UPS crunch.
The UPS Store that Rob uses to ship his scopes still uses foam peanuts which is a pain in the butt. The bits and pieces get everywhere including inside the boundary layer fans. It took a few hours to unpack and clean up the mess which I finished the next day. I have six 13 gallon garbage bags filled with the foam peanuts that I will save for other uses. The large boxes that the UPS Store used were made from as many as 12 pieces of cardboard resulting in a pretty weak structure held together with yards and yards of tape. I’m amazed that they made the trip from New Jersey is as good a condition as they did. They really ought to have large boxes made properly, or at least know how to construct one odd sized box from maybe two others to maintain a bit of structural rigidity.
Enough of that.
ASSEMBLY OF THE TELESCOPE
One of the nice touches that Rob includes with the scope is a black 3-ring binder containing all of the manufacturers’ brochures and instructions in plastic sleeves. He also sent custom assembly instructions via email which I printed out and included in the binder. The binder’s cover insert has the Teeter’s Telescopes logo, a photo of my personal scope and text that states “14.5” f/4.5 Ultra-Limited-Edition” above the photo and “Custom Designed and Built for Jim & Leslie Cole” below the photo. A very nice touch.
Following the instructions that Rob sent, the assembly went very smoothly except for four annoyances.
- The first one occurred when I was moving the UTA after pulling it out of the shipping box and noticed that the Crown Royal pouch that Rob uses to cover the secondary was swinging back and forth. I loosened the bag from the secondary support, opened it up and discovered that the secondary mirror had fallen out of the ProtoStar holder. My heart skipped a beat, but a quick inspection showed that the super soft Crown Royal bag had saved the secondary mirror from any damage. I had another moment of elevated heart rate when I thought about what would have happened if the mirror had let loose after assembling the telescope with the primary in place. I wiped the sweat from my brow and pushed the thought from my mind.A note to all buyers of dobs from any manufacturer: Please check the security of your secondary mirror as the sometimes brutal handling of packages by parcel delivery services can result in a compromised mounting. Rob is adding a warning in his assembly instructions as well.
After inspecting the ProtoStar holder, I initially thought that one of the three metal tabs that holds the mirror in place was deformed, but that was not the case. It turned out that the washer under the screw that holds the metal secondary shroud together at the top of the mirror had slipped out of place allowing the shroud to open and drop the mirror. See Figure 5. I carefully reassembled the shroud and mirror and made sure that the screw and washer were placed properly. I know my scope was the last Teeter to use ProtoStar’s spider assembly and found out from Rob that the Astro Systems secondary mounts that he now uses in all his current builds use two screws, one on each side of the shroud to prevent this from happening. I should have gone with Rob’s suggestion. This design defect still makes me nervous.
- The second issue was during the primary mirror install when I noticed that the three rubber bumpers that should be about 1/8” from the edges of the mirror were more like ½” when rotated to the best position. It’s like the mirror cell was made for a larger mirror. I didn’t think too much of this until I tried to collimate the scope and noticed that the mirror could move back and forth (left and right) on the cable sling by as much as ½” or more and stay in that position held with the friction of the 18 flotation points on the back of the mirror. This caused some axial alignment issues during my first collimation, but once I figured out what was going on and manually centered the mirror, collimation was much easier. Rob has contacted the manufacturer of the mirror cell and a fix (a set of bumpers with a larger diameter) is in the works. Again, very responsive customer service. To be fair, Rob noticed the oversized mirror cell and would have had this fix done prior to delivery if I hadn’t put him into “Rush” mode. Several late deliveries or “out of spec” mirror cells has led Rob to start working with a new mirror cell manufacturer for future builds. Good news for future owners.
- The third issue was when I noticed that the mounting hole on the focuser board was bigger than the focuser. A good 3/8” space is between the top of the focuser and the focuser itself although the mounting screws are solidly attached. There is also about 1/8” space on each of the sides. The hole looks like it was drilled for a bigger focuser. My concerns were twofold. First, that it looked completely wrong on a scope where every other detail in workmanship is flawless and second that it can allow stray light to enter the UTA and strike the secondary mirror, reducing contrast. In fact, after talking with Rob and expressing my concerns he told me that he uses just one stock board to fit the larger FeatherTouch and the smaller Moonlight and that stray light shouldn’t be a problem as direct light is blocked by the viewers head and light originating from the sides or top would have a harder time causing a reduction in contrast. Rob suggested that I use it for a while and if it still bothered me we would come up with a solution. I think the thing that most bothers me is the fact that on a custom scope, he would use a focusing board not properly drilled for the focuser I had ordered. Since all of the wood is cut to order at a mill, I’m not sure why having the focuser hole cut to spec would be a problem. Every time I look at it, it looks mis-manufactured and whispers to me that I shouldn’t have cheaped out on my chosen focuser. “The FeatherTouch would have fit”, my brain says. I guess that I should do a comparison test with the holes stuffed with some black material. Still, I have a feeling that when my neighbors porch light is on and the focuser is on that side of the scope, something has to happen. I think I’ll do a quick test and then take Rob up on his suggestion to discuss a fix. Regardless of whether or not there is contrast loss, I don’t like the way it looks. Period. Sorry, but I’m a bit OCD on this kind of stuff.
- The fourth was that I had ordered a gold anodized Moonlight focuser but the scope showed up with the standard black one. Rob simply fumbled that one, but he apologized profusely and offered to send me the correct replacement which I would need to install. After thinking about it for a while, I decided that I’m fine with the black one. The gold might have been over-the-top bling anyway. The error made in my favor.
Figure 5. This screw jarred loose and dropped the secondary into the Crown Royal bag saving damage.
Figure 6. The (in my opinion) too large hole for the Moonlight focuser.
The rest of the assembly was a snap. The installation of the primary mirror into the Glatter Sling was simple with the mirror cell’s tailgate design which allows it to drop down out of the tilted mirror box to a horizontal position to work. The Moonlight trusses with ball-heads and attachment boxes are elegant and simple to use. The cables for the ProtoStar dew heater and boundary layer fans are positioned for a quick and easy connections, The Kendrick controller box uses velcro to attach to the mirror box and the battery sits in the rocker box just under the Kendrick. Rob installed the hardware kit for the Sky Commander which I will add later. I installed the StellarVue 10x60 finder into the already mounted Losmandy rings and snapped the Rigel Quik Finder into the already mounted base. Everything looked perfect. After assembling the telescope, I had to stand back and admire the quality of the workmanship for a few minutes. It really is gorgeous and solid as a rock.
Next, I put my 2.2 lb. 28mm UWAN (same weight as a 31 Nagler) into the focuser with the Paracorr to see if the scope would hold balance throughout the range of altitudes which it did beautifully. I then removed the 28 with the Paracorr and inserted one of my new, extremely light StarSplitter eyepieces in the Moonlight 1 ¼” adapter and checked for balance again. Unbelievable…no tendency to float. “What the heck”, I say to myself, “let's see what happens with the new ES 30mm”. I had bought this 3.2 lb. eyepiece just to compare to the UWAN. I put the ES into the Paracorr and put the combo into the Moonlight focuser. Once again, the balance was fine all the way through 90º of motion. Excellent!
Figure 7. The Glatter Cable Sling held to the mirror’s center of gravity by three split pieces of velcro.
Then I did the first collimation check. I used a combination of the full set of 2” CatsEye tools including the dual pupil autocollimator along with a Glatter laser that I’ve had for many years and a new TuBlug. Having been out of the dob game for a while it took a little while to wrap my head around what each tool could do. I only used the sight tube (adjusted for an f4.4 mirror) once to check that Rob had the secondary properly centered and that I didn’t mess it up with the reinstall of the secondary mirror. I didn’t. As discussed previously, the out of spec mirror cell caused the collimation to be off by quite a bit. It took me a while to get the collimation right the first time, not only because I was familiarizing myself with the process all over again using new tools, but because I was also dealing with the shifting mirror issue that I hadn’t figured out yet.
FIRST LIGHT IN FLAGSTAFF
Thursday evening after the packing mess was cleaned up and with the scope assembled and collimated, a quick look outside at the evening sky told me that I had avoided the new scope curse since I really had planned to first light the scope at the TSP. I caught the curse off guard with my last minute decision to take the scope outside on my backyard patio. HA!
Since I was missing two wheelbarrow bolts and I didn’t have any substitutes in my parts bin, I had to carry the scope from the living room about 30 feet to the patio. This gave me a chance to use Rob’s brilliant “Truss Ring” feature (See Figure 9). Off came four rubber coated hand bolts and the entire top truss and UTA assembly lifted right off the mirror box in one solid, easy to carry structure. Out came the mirror box with the installed mirror to set on the floor. I did not get a chance to weigh all of the components, but the mirror box lifted with the huge altitude bearings was just within my capability to walk and carry with small steps. Oh yeah, before carrying any pieces through the open patio door, my three cats were secured in back rooms so I wouldn’t trip over one of the curious little fuzz balls.
Figure 8. The 18-point mirror cell with the mirror cell and sliding ball bearing barrels of the Glatter Sling. The tailgate allows the mirror assembly to drop down for easy mirror removal by removing the two brass thumbscrew on either side at the top. The mirror cell and hand collimation knobs are a darker gray than they appear in this image.
Out went the rocker box with its attached ground board followed by the mirror box and then the upper truss assembly. The ground board has three nice thick conical-shaped rubber feet which sit on the ground. This makes the base feel extremely well planted. The 24” wide mirror box fit easily through my 34” wide door. The mirror box with the wheelbarrow handles attached will be 28” wide, still plenty of room to wheel it out through the patio door. It took a minute to reattach the upper assembly to the mirror box and attach the dew heater cable to the UTA and to the Kendrick controller and another 10 minutes to re-dial in the collimation due to the shifting mirror issue.
After a few more practice sessions at the TSP, I could get very nice results pretty quickly with all of the tools and the new HotSpot center spot. Currently, my normal collimation procedure is:
- Set the altitude of the scope to about 50-60º (since most of my viewing is between 30º and 80º)
- Put the 2” laser in the focuser and make sure the dot hits the center of the HotSpot. Adjust the three collimation screws on the secondary if necessary.
- Remove the laser and put in the 2” CatsEye Cheshire. Adjust the primary collimation hand-bolts to center the HotSpot perfectly in the cheshire’s ring.
- Remove the Cheshire and put in the 2” Autocollimator. Use the center pupil to line up the correct reflections by adjusting the secondary screws again and fine tune with the off-set pupil.
- Repeat steps 2 and 3 once or twice if I’m feeling a fit of obsessive compulsive disorder.
- Just before viewing, put the laser into the TuBlug and make a final quick adjustment of the primary mirror hand-bolts if needed.
- Start Viewing!
- Use the laser and TuBlug to check collimation periodically during the night.
Figure 9. The upper telescope assembly separated from the mirror box with Rob’s Truss Ring design.
I hooked up the battery to the Kendrick controller, turned on the boundary layer fans and let them run while I went back inside to eat dinner and wait for darkness. After dark, it took a couple of minutes to align the Rigel and SV finders, and then I put the Paracorr in the focuser. The final thing I did for the setup was to remove the stock eyepiece from the SV F60 finder and put in a new Panoptic 24mm that I had bought just for the finder. It provided a cleaner, sharper and wider view than the stock eyepiece. I was ready to find some old favorites. My wife joined me on the patio and everything seemed right again.
Figure 10. The mirror in the Astro Sky custom hardwood box after Rob positioned the new CatsEye HotSpot.
Figure 11. The Kendrick dew and fan controller and the 12v 7Ah battery. The fans plug in on the left side of the controller and the secondary dew heater, when needed, would plug in to one of the programmable sockets on the right. Two grill covered air holes along with 5 uncovered holes provide an exit for the 204 cfm of air pushed over the mirror by the dual boundary layer fans. Fat pneumatic tires on nice gold rims dress up even the wheel barrow handles.
The first target was Saturn. I centered the planet in the Rigel, confirmed position in the F60 and then took the first look through my new 28mm UWAN. A little miniature Saturn was there in a beautiful wide field view of the stars of Virgo. Obviously 64x wasn’t going to do it so in went the old trusty 9mm T1 Nagler. The transparency was excellent, but the seeing only average so that 207x was about all it would take. Saturn was beautiful as always with momentary crisp views coming about 5-10% of the time. My wife spent several minutes at the eyepiece enjoying the view.
I moved the telescope to Berenice’s Hair and put back the 28 UWAN to get a quick idea of the quality of the eyepiece. I needed to raise the eyecup a couple of turns and at that point I could rest my cheek bone and eyebrow on the eyecup and get a comfortable 1.2º actual field in the 82º eyepiece. I had guessed a setting of 3 on the Paracorr for starters which was good enough for first light. The eyepiece was filled with pinpoint stars almost all the way to the edge with a couple of galaxies to boot. I was a happy camper!
Next I went to find M81 and M82 to see if they would fit nicely in the FOV of the UWAN. Out came the S&T Pocket Atlas, because I couldn’t remember where they were. Two or three minutes later, I was surprised to see the pair in the F60 finder. I never had used other than a Telrad with my previous telescope and suddenly discovered that I was really going to like using the F60 with its 6.4º FOV. In the UWAN the galaxy pair was spread nicely across about 60% of the view with some 100 pinpoint stars sharing the dark sky. No hurry to rush to a higher power. My wife and I took turns sharing the view for many minutes and very broad smiles began to spread across our faces. This is what we had missed for the last several years. The flame within started to rage again.
Final target for the night was M51. Again a quick glance at the Pocket Atlas to jog my memory, I placed the Rigel circles where I thought it should be, checked the F60 and saw a very faint smudge of light just off-center in the field of view. A quick nudge of the telescope brought it to center and there it was in the eyepiece. This object, of course, required an immediate boost in power , so out with the 28mm and in with the 16 and then the 9 Nagler. The seeing prevented a really exceptional view, but some structure of the spiral arms could just be made out on the mottled surface of the galaxy. Still, one of the most beautiful sights in the night sky.
I was wishing for better seeing to do a star test and try out some of my new higher power eyepieces, but that was not to be. My goal for that night was just to test out the basic functionality of the telescope. It passed with flying colors. It was now 10:30pm and time to pack it in. Next stop, the Texas Star Party.
SIX NIGHTS AT THE TEXAS STAR PARTY
I arrived at the Prude Ranch on Sunday and played peek-a-boo with the clouds. Monday and Tuesday were the best days, although hampered by less than expected transparency and rather average seeing as were all the nights that week in west Texas. Regardless I pulled all-nighters on both nights. Wednesday was another peek-a-boo night and I called it quits around 2am. Thursday I decided to sit in the observing field, drink beer and tell tall tales with a buddy from North Carolina and we were shortly joined by a couple of Canadians. The sky was socked in by 11:30 or so. Friday night was a repeat. When I saw that Saturday night called for more of the same, I decided to leave a day early. Several days were cursed with high winds which caused a more than a few unfortunate telescope mishaps. My Teeter, covered in its new Telegizmos cover and strapped down to stakes, pulled through unscathed. I love the fit of the new cover, by the way. Simple to put on and take off.
The lack of good seeing once again foiled my attempts to do a real star test and play with my new higher power eyepieces. I was limited on most objects to 150x to 200x. The scope when uncovered during early evening hours got a lot of comments from passers by about the sheer beauty of the workmanship. It is funny that no one even noticed the large focuser hole, so maybe I’m being obsessive or the early evening light made it less noticeable. Other folks who stopped by after dark for a visit were impressed with the views as well as the feel of the scope.
I won’t bore you with the observing details except to say that I spent time logging 20 new Herschel 400 objects and an equal time playing with some old favorite showpieces. It took a few hours for the old learned skills to kick in again after such a long absence, but shortly I was back in the groove of hunting, finding, logging and sketching. Poor transparency was confirmed on two different nights with the inability to see the 13.9m central star in the Dumbbell nebula at any power up to 278x except with averted vision.
Figure 12. The beautiful details of the oversized altitude bearings, mirror box cover, truss ring and Moonlight truss components.
Figure 13. The brass details of the mirror box with dual boundary layer fans and the new on/off switch.
Figure 14. The UTA with the StellarVue 10x60 finder, Rigel Quik Finder, Moonlight focuser and UWAN 28mm.
Figure 15. Looking down the UTA. The top of the secondary holder looks artificially light in this image. It is a flat black as expected.
SUMMARY AND CONCLUSIONS
OK, so here’s the final summary of current impressions of my new Teeter:
- Working through the order and build process with Rob was always a pleasure. He is a consummate professional, always willing to consider and discuss any idea. Very highly recommended, both for his teamwork attitude and his skills as a telescope maker.
- The telescope is a work of art. Build quality, staining, painting and hardware are first quality. Nice functional touches include flocking of the UTA opposite the focuser and a flocked baffle above the mirror in the mirror box. This scope definitely outperforms my old scope with the same mirror due to the larger diameter UTA and the larger, 3.1” 1/20 wave quartz secondary. My old Jupiter dob had a UTA diameter of only 15.5 inches which according to what I understand now, was causing vignetting. Along with a slightly undersized 2.5” secondary, I was probably getting the equivalent of a 12.5” or 13” scope. The larger UTA also keeps the focuser draw tube from intruding into the light path. Even with the average seeing and transparency in Texas, the scope gave noticeably better views of the Omega and Lagoon Nebula than anything I remember from Florida or Flagstaff in the old scope. The final night’s viewing, again in average conditions, of M51 and M101 at 207x at the TSP had me, a 15” Obsession owner next to me and two other visitors held in a state of awe as we all agreed that it was the best views of both galaxies any of us had ever had in a medium sized dob. This could be more than partially be due to the boundary layer fans discussed in #4 below and the improved mirror support discussed in #6 below.
- Take down and set up including the attachment of the UTA is a breeze with the Moonlight truss system and the Rob’s truss ring design. Upon returning home and receiving the replacement wheelbarrow handle bolts from Rob, I had a chance to again to make use of the truss ring feature and rolled out the lower assembly to my patio with ease using the wheels, attached the upper assembly and did a quick collimation. I was ready to go within 10 minutes of making the decision to go outside for a viewing session. I just love rolling the scope on those big fat tires.
- The boundary layer fans are now accepted as a necessary feature in any large newtonian. The dual fans are mounted using Sorbothane pads to reduce vibration and do a very good job, although they do not eliminate it completely at high power. Although the cooling function wasn’t as important in Texas where the scope sat outside all day and the nighttime temperatures didn’t fall as fast or as far as in northern Arizona, the ability to scrub the boundary layer at will came in handy. Several times at the TSP when I thought that the seeing had gotten suddenly worse, I switched on the fans to scrub the boundary layer for a few seconds and the previous seeing was restored. These moments made me think back to all the years of using my old Jupiter scope and never extracting the full potential it had.
- The Moonlight focuser with dual ratio controls operates like butter and got several positive comments from visiting viewers. The fine focus feature is terrific.
- I like the Glatter cable sling for it’s elegant simplicity, but I was unable to enjoy its invisibility because of the issue with the too big mirror cell and the more difficult collimation I had to deal with until I had the problem figured out. When the new bumpers arrive, the mirror will be more stabilized making collimation simpler each time the scope is moved. To be clear, this problem is not related at all to Howie’s fine sling. My old Jupiter had a traditional mirror cell that gripped the mirror snugly at three points and the mirror never moved. This may have been another contributing factor to the better performance of the old mirror in the Teeter structure using the cable sling.
Edit 06/12/10: the new bumpers arrived and were placed into the mirror cell. Now the mirror cannot move more than a hair’s width side-to-side so collimating after moving the telescope only requires a quick adjustment or two.
- The StellarVue 10x60 RACI finder is a wonderful accessory that I added late in the process (I actually ordered the 9x50 but it was upgraded by Rob). I really enjoy the fine views with the Panoptic 24mm eyepiece and used it several times to investigate objects found in its large field of view after centering it on the original object of interest. Lots of NGC objects are visible in this fine 60mm telescope.
- The Rigel Quik Finder is small, light, quick to mount and dismount and very easy to align. The built-in dimmer is a huge plus, too. It is definitely harder to gain proper eye position than with the Telrad and a bit frustrating at times, but I’m getting better at it. It is small enough to fit right into my eyepiece case when not on the telescope. It takes up only a little more room than one of my Siebert StarSplitter eyepieces.
- I have already discussed the ability of this telescope to maintain balance over a wide range of weight added to the focuser. This is due to the oversized altitude bearings and the fact that Rob leaves the EbonyStar (E*) naked with no wax. Rob also uses the AstroSystems Teflon kit for the rocker box and ground board assembly which uses a 4th block of teflon around the center bolt for additional support. The trade off with the unwaxed E* is a bit more stiction (necessary force to initiate telescope movement) that becomes a bit of an issue at higher powers where the scope feels, well, sticky. Waxing of the E* is considered a no-no by many since it attracts dirt and dust and leads to the eventual deterioration of the E*. Others don’t seem to have a problem with it, including Rob who suggests a light waxing with a good quality paste once a year. I have to see if I can find an acceptable trade off between balance, stiction and durability. There are some options which are beyond the scope of this review that I will be considering. In the end, I may do nothing.
- The rubber feet on the ground board make for a solid mating to the ground but make it more difficult to slide it across the surface in the back of my Jeep or the carpet in my living room. I think I’ll start using a trio of furniture sliders to eliminate that issue. I do really like that way the board sits on the ground with the rubber feet. It feels very connected. My old Jupiter had wood blocks for feet and never felt quite stable on hard, rough ground like at the TSP.
- The flocking across from the focuser and the flocked baffle above the mirror seem to do a very good job of allowing the telescope to provide all the contrast it can. I have not really used the telescope in a strongly light polluted environment yet (that will happen when I move to Indianapolis soon), so I cannot speak to the trials of trying to view with streetlights everywhere and whether or not the UTA is deep enough. The top of the focuser is a good 6.5” below the rim of the UTA which seems sufficient.
- The lack of dew means that I did not need to test the ProtoStar secondary dew heater other than to make sure the red indicator LED came on when powered up. Dew heaters are rarely needed in northern Arizona or west Texas and this was bought with future moves to Indianapolis and Redmond, Washington in mind.
- The structure is fairly stable. At no time with my hand resting on the UTA for guiding did I see any vibration in the eyepiece, medium power or low (remember, I haven’t had a chance to do any high power viewing). Likewise, resting my face against the 28mm UWAN during viewing had no effect whatsoever.
- In my normal viewing range between 30º and 80º of altitude, there is virtually nonexistent collimation drift. At 90º there is about 1mm of drift and at 20º or below, which is rarely used, the drift increases to about 1.5-2mm. Having no other telescope to compare these numbers to, I do not know how the Teeter stacks up in terms of its ability to hold collimation. I would like to retest the drift after I receive the new mirror cell bumpers, reinstall the mirror, even out the collimation knob positions and do an entire optical alignment again. Part of the drift could be due to my “rush to the TSP” setup.
Edit 06/12/10: After installing the new mirror bumpers and readjusting the three mirror clips closer to the mirror’s surface, the collimation drift below 20º has been reduced to about 1 mm. The larger drift before was caused by the sling supported mirror falling forward in the cell to the too-high upper clip. Now that the clip is closer, it can only move a short distance forward and so the drift is now reduced accordingly. I have a feeling that the drift at the zenith is due to the weight of the mirror settling onto the felt supporting pads and causing a bit of movement. Maybe those pads should be a hard rubber. I do admit to not observing near the zenith very often as I hate controlling the scope in the dobson hole. It’s good to know that the structure itself is contributing to very little or none of the collimation drift.
- The only remaining issues are the aforementioned out of spec mirror cell and the oversized hole for the focuser. For me, the mirror cell issue is being taken care of as we speak with the larger bumpers on their way (Edit: this happened on 06/12. See #6 above). For all future owners, you will be getting mirror cells from a better, more consistent fabricator. The oversized focuser hole is still under consideration. I know that if I decide that the larger hole bugs me too much to live with, Rob will make it right. That’s just what he does.
Overall, I am extremely happy with the performance of the scope and would gladly tell anyone considering a new dobsonian to consider the quality and experience of owning a Teeter’s Telescope.
Figure 16. The Teeter in its “ready to go” storage place in my family room with an eyepiece case, an accessory case, a soft case holding books and charts, notebook and a small case for my collimation tools.
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