Saturday, March 28, 2009

 

Rebirth of a Telescope

Hard as it is for me to believe, it’s been going on six years since I started work on my “city observing book,” which was published in ought-six as The Urban Astronomer’s Guide. I don’t think any author is ever fully satisfied with the results of their labors, but Urban Astronomer comes purty danged close for me. But my purpose here today is not to tell y’all how great a book it is, or to convince you to buy it (though I wouldn’t mind), but to tell the story of one of the telescopes integral to its writing, an 8-inch German equatorial-mounted Newtonian a “GEM Newt.”

If you ain’t been reading this here blog every week, you might be surprised to hear a dadgummed Newt is integral to anything I do. Ain’t I “Mr. SCT”? I’ve been called that, and that is not a title I shrink from, but if you have been readin’t this blog faithfully, you know SCTs ain’t the only scopes I use. I’ve long been a firm believer in “right tool for the job,” and while the versatility of the CATs means one is often that right tool, not always. After fifteen years, my Meade 12.5-inch Dob, or what’s left of her, for example, still gets frequent doses of starlight. Not only does she bring considerable aperture in a small package to the table, there’s sometimes just something restful about the good ol’ nudge-look, nudge-look as opposed to the computers, cables, and grinding motors that often accompany a modern SCT into the field.

But a need for the right tool wasn’t why I glommed onto a GEM Newt. The reason was that Urban Astronomer was to be a general interest book aimed at all amateur astronomers, not just SCT fanatics. One of my principal theses would be that almost any telescope can be used for city-bound astronomy. Problem was, while I had a (sorta) large Newtonian, the aforementioned Dobbie, and a small one, my beloved Pal Junior, I didn’t have a medium-sized reflector any more, and as I would stress the book, 8-inches really is the baseline for observing fruitfully from light-pollution hell. I had had one, a Coulter 8-inch f/7, but it had gone to a good home where it would actually get used some time before I started Urban Astronomer. I would need, I thought, a Newt in the 6 – 8-inch range to properly serve my audience. But which Newtonian?

Thumbing through the Orion catalog, it was obvious I could pick-up one of their minimalist 8-inch Dobsonians for a song, just a tad over 300 bucks. Which would be fine, no doubt about it. And yet…and yet…paging on revealed an old-fashioned twist on 8-inchers that had suddenly come back around thanks to the endlessly churning Chinese Telescope factories: an 8-inch equatorial reflector. Thirty years ago, the GEM-Newt was still a staple of amateurs, but as SCTs and Bigdobs came ever more to rule the roost, German mounted reflectors headed for that laaaast roundup. The famous Edmunds and Starliners and Caves and Optical Craftsmen and Criterions vanishing from the scene as if they had never been. Which was kinda sad, since a GEM Newt does have at least one plus its Dob descendents usually don’t: trackin’. If you want to do high power observing, any power sketching, or most photography, the beauty of one of these scopes becomes apparent.

"Apparent" to the far eastern telescope makers and western telescope importers anyhow, as there’s been a real revival, a rebirth of this forgotten telescope over the last decade. That’s become possible for one reason and one reason only: the inexpensive but effective Synta EQ4/CG5 mount (and similar clones of the Vixen Great Polaris). An 8-inch f/5 or 6-inch f/6 OTA is, if not perfectly suited for one of these GEMs, at least highly usable on one. The OTAs? The Chinese have mastered making good (not great, but good) optics cheaply and housing them in inexpensive but functional tube assemblies. Combine the two and you have the modern GEM Newt, not quite a Cave, no, but not bad neither.

Tracking appealed to me. I’d be featuring a lot of eyepiece field drawings in the book, and having to hold pencil and paper, draw, and nudge the scope along was not my idea of a good time. Sure, I coulda investigated Dob drivers and equatorial platforms and suchlike, but I was pretty sure the combination of even an inexpensive Orion or other import 8-inch and one of these solutions would bust the very small budget I had established for book-related expenses—about 500 bucks. Unfortunately, it appeared an 8-inch Orion Gem Newt would bust that budget too, by about one C Note. I could drop back to one of their 6-inch GEM scopes, but, again, I have come to believe 8-inches is really the lower limit (all things being equal, which they rarely are) for urban astronomers. My perplexed state only maintained for a while, till one of my few remaining brain cells fired and I said to myself, “Self, I bet Orion ain’t the only outfit sellin’ EQ4-mounted 8-inch Newtonians. I betcha somebody without a big color catalog to print and mail is undercutting the Watsonville gang.”

A little poking around on the Internet revealed that was indeed the case. I turned up several 8-inchers that hovered just below or above the budget deficit level. The cheapest of all was from Konus. Who dat? Konus is an Italian company that used to sell some fairly upscale gear, but which in recent years had begun selling inexpensive Chinese scopes, today the cheapest they can get their paws on, telescopes decidedly down the quality ladder from Synta. When I undertook my search, they was still selling Synta gear, however, if Synta gear that was sometimes slightly cheapified over what the Chinese Scope Giant doled out to Orion. Be that as it may have been, I found an 8-incher with dual axis drives included (usually an option on the Orions) along with a couple of cheap Plössl eyepieces, a Moon filter, a 50-mm finder, and the EQ4 mount for, yeah, 500 bucks. I wasted no time in dispatching my credit card number to the U.S. distributor (since gone) who was the Konus outlet at the time.

In a little while as the Brown Truck Boys measure time, a largish box showed up on Chaos Manor South’s front porch. I was excited as hell, or at least as curious as hell, anyway. What could somebody sell me for about twice the price of the extremely rudimentary Coulter 8-inch f/7? How good could an 8-inch scope on a dual axis driven mount be at this price level? What would come out of that big box?

OH! MY! GOD! MY EYES, MY EYES! If you’ve ever seen one of Konus’ OTAs in person, you know what I am talking about. When I pulled the tube assembly from the box and removed its protective paper wrappin’ I was confronted by the notorious Konus Yellow, a shade somewhere between Florescent Orange and Baby Poop. If you think Celestron Orange is brash, well you ain’t seen nothing! Once I got over the shock (and flash-blindness), I allowed as how the OTA appearance was “distinctive,” if nuttin’ else—meaning you wouldn’t lose it on a crowded observing field, even in the middle of the night.

Otherwise? Most of the OTA was good or OK. The tube was seamed, rolled steel. Mite thin, but sturdy enough and light enough. There was a surprisingly good 9x50 finder. The secondary holder/spider was a minimalist affair, with the secondary mirror glued onto the end of a strut. This secondary was easy enough to collimate, but in typical import fashion, that required a small Allen wrench. The spider that held up the secondary was fine, the vanes were a little thin, I thought, but that was better than too thick I reckoned. The tube was held in a couple of hinged and felt-lined rings that could be loosened to rotate the eyepiece to comfortable viewing positions. These rings were perched on a Vixen-style dovetail bar that, while skinny for an 8-inch f/5 Newtonian OTA, did the job. The aperture cover was a nice plastic affair that snapped snugly over the tube end. Removing this cover an’ peering down the tube revealed a primary that was nice and bright and—surprisingly enough—already center-dotted with a small paper-reinforcer ring.

That was the good/fine, though. I immediately noticed a couple of sore points. First was the focuser. Today, the Chinese megafactories are turning out Crayford focusers that are, frankly, a wonder. They are cheap yet blessed with action smooth and precise enough to make them fully competitive with Crayfords costing two or three times as much. In 2003, though, Synta was still a-using a 2-inch rack and pinion job that was something of a pain. This rack and pinion was cursed with a focus action that was invariably too hard or too easy no matter how the teensy weensy Allen screws on its underside were adjusted. I did the best I could and left it at “a little too stiff” in order to preclude drawtube wobble and focus shift.

The only other downcheck I toted-up was the primary cell. Mostly it was OK, working, as most Chinese mirror cells do, via pairs of push/pull bolts. The bad part was that it was covered with a metal cover that completely sealed the end of the tube. This would need to be removed to speed cool down, but doing so exposed the bare back of the mirror. I was concerned about reflected light from the ground in light polluted areas being transmitted through the primary. Since I intended to use the scope in badly light polluted locales, I left the cover plate on—it usually don’t get cold enough down here to worry about cool down to much anyhow.

Even moreso than the OTA, I was curious about the GEM mount. Mostly I was pleased. The head was the ubiquitous, then and now, Synta EQ4 (which the company’s Celestron division calls the “CG5”). The one I received with the Konus was a second generation EQ4, meaning the RA axis had been equipped with decent bearings, at least as compared to the very stiff early models. Some assembly was required, but other than attaching mount to tripod via a threaded knob, that consisted only of bolting the RA and declination motors onto their respective axes, a 5-minute job. Included with the drive motors was a little hand control paddle allowing the selection of a slightly higher centering (not slewing) speed, a north-south switch, and, of course, four direction buttons. The drive system was powered by four D cells in one o’ them little vinyl “purse” style battery holders that, like the HC, was virtually identical to what Vixen was equipping their mounts with a decade or two previously. The Konus GEM shipped with three of Synta’s 11-pound “pancake” counterweights. One nice inclusion, often an extra cost option with the Celestron and Orion versions of the mount, was a workable if not optimum polar alignment borescope (the view through it being narrow and dim).

The only noticeable deficiency in the mount was the tripod. Not only were its 1.5-inch diameter legs a little skinny for a sizable 8-inch Newtonian, the fittings at the tops of the steel legs where they attached to the tripod head were plastic rather than metal, something that was obviously gonna cause flex and shakiness. That was aided and abetted by a wrongheaded decision on the part of whoever designed the tripod not to use a tripod leg spreader bracket. Most Synta GEMs have a metal spreader through which passes a threaded rod. This rod screws into the bottom of the mount head at the top end, and is tightened against the tripod spreader with a knob at the lower end. This adds greatly to overall tripod steadiness. The Konus had none of this. In lieu of the spreader there was an accessory tray attached to the tripod by small, hinged brackets. The head was fixed to the tripod via a captive knob-headed bolt. I also noted that the accessory tray didn’t really spread the legs far enough apart to ensure a steady support for the scope. It didn’t tip over as I maneuvered the tube around, but it threatened to a time or three. The only saving grace as far a I could see, once I had the scope fully assembled, was that given the height of the eyepiece in most observing positions, there would never be a need to extend the legs of the flimsy tripod.

My reaction once I had the thing assembled before me in Chaos Manor South’s living room? Once I got over my shock at how dadgummed Yellow the Konus was, I couldn’t help bein’ a little impressed. Despite the florescent baby poop hue, the 8-inch just looked cool. This was mostly nostalgia, I reckon; somebody who, like Unk, grew up in the amateur astronomy of the 1960s just naturally has a soft spot way down deep in the most cynical and shrunken of hearts for that icon of the age, the big GEM Newt. And, in terms of my childhood, this was one big scope. An 8-inch. Same aperture as Edmund’s much-lusted-after but impossible to afford (for me and my lower middle class mates, anyway) 8-inch reflector. No, it didn’t have quite the heft of the Edmund, but based on bitter experience with heavy but shaky 1960s GEMs, I suspected the Konus might perform every bit as well. I knew, as always, though, that a living room ain’t no proving ground for a scope, only an observing field will allow one to show its mettle.

The Konus, who I’d taken to calling “Old Yeller,” got a chance to prove herself shortly. Surprisingly, the vaunted New Scope Curse did not strike. Maybe 500 simoleons of telescope just warn’t enough to anger the weather gods. Anyhoo, the late spring – early summer skies were amazingly clear when I hauled the scope out to one of my prime “City Lights” observing stations, the public schools’ Environmental Studies Center. This tract of land, which features a nice, open field, had become heavily light polluted as the city had flowed around it, but that was, for once, all to the good considering the nature of my project.

Transporting Ol’ Yeller was no problem. At f/5, the OTA fit in the back seat of the Camry with room to spare, and the tripod and GEM head took up but a small corner in the trunk. Assembly was a job of maybe five minutes. That done, the first question was “how good the optics”? The answer was, “amazingly good.” A star test revealed that the primary, while maybe a hair rough, as is often the case with mass-produced machine-made optics, was quite well corrected. A glance at a young Moon plunging into the west bolstered that finding. With a 2x TeleVue Big Barlow and a 12-mm Nagler II eyepiece, what little terminator was visible was beautifully detailed and fascinating despite Luna’s low altitude. Jupiter, hovering over in the west, was the next target. I was lucky enough to catch the Great Red Spot transiting, and it was starkly obvious despite its pale color at the time. Looking at Jupe did reveal one of the scope’s weak points. Oh, not a problem with the Konus per se, but a problem for any 8-inch f/5 if planetary observing is the main course. Even with a 2x Barlow added to the 12-mm, I was only gettin’ 166x outa the scope. 1000-mm of focal length makes it hard to develop much magnification without resorting to high power Barlows and short focal length (and uncomfortable to use) eyepieces.

How did the mount perform at this semi-high power? Adequately. I won’t say it was the Rock of Gibraltar, but it was at least a little steadier than my beloved Palomar Junior or any of the many hallowed RV-6 Dynascopes I’ve used over the years. I believe the Celestron vibration suppression pads I put under the tripod leg tips helped Ol’ Yeller’s puny tripod a lot. What hurt? The unavoidable stiffness of the focuser made sharpening up Jupe somewhat frustrating.

How about the drive? It was OK. Despite a mere “eyeball it” polar alignment, Jupe stayed centered for long periods with only the occasional mash of a N/S button. I did note that, like many Chinese mounts then and now, there was a lot of backlash in the declination axis. Carefully adjusting the gear mesh later helped, but I finally concluded that much of the problem originated in the declination motor’s “loose” transfer gears, and that the backlash purty much had to be lived with (keeping the mount slightly unbalanced in declination helped a little). Having had some exposure to power-hungry go-to mounts by this time, I was a little concerned about the drive’s use of D batteries for power. I needn’t have worried; with no computer and no high-speed slews, it turned out the batteries lasted for long periods.

I was gratified the Konus performed well on the Moon and Jupiter. Looked like I’d got my money’s worth. There still remained the question of how well it would do as a tool for observing the deep sky and, specifically, for helping me make the observations I needed for my book. The answer was “mostly good, only a little bad.” As I began working the Cygnus starfields, doing the many open clusters to be featured in Urban Astronomer, I was both impressed and frustrated. I was impressed by the telescope’s sharp, expansive optics. At f/5, you have got one hell of a lot of good-looking field to play with. When I was in a part of the sky (near zenith) dark enough for it to prove effective, my beloved 35-mm Panoptic chomped off giant sized bites of Milky Way. At first I found the diffraction spikes on bright stars caused by the Newtonian’s spider secondary support distracting, but I soon got used to them. How ‘bout contrast? There might have been some roughness to the primary, but not enough to harm images. The Konus showed up M101 almost as well as the C11; not a trivial feat in sodium orange skies. As I’d suspected, field sketching was much easier with the driven GEM than it would have been with a Dob—MUCHO easier.

But, yeah, I was frustrated, too, muchachos. That had nuttin’ to do with the Konus, but with my lack of experience in recent years with non-go-to GEMs. I’d center my target in Ol’ Yeller’s generous finder, and then find myself unable to find them frakkin’ RA and declination locks. By the time I did locate them levers, I’d almost inevitably have bumped the scope off target. Yeah, I reckoned I’d eventually get used to the routine, but I wasn’t sure I wanted to get used to it. I ran into the same frustration with a Vixen GP mounted C5 that the good folk at the 2007 Almost Heaven Star Party kindly arranged for scopeless Rod to use.

All summer and into the fall, the Konus just rocked on, never missing a beat, pullin’ some amazingly faint fuzzies out of b-a-d skies every time I had her out. I even did a little imaging. Oh, not of the deep sky, though I suppose you could do that with a dead-on polar alignment (so you wouldn’t have to make too many declination adjustments), but of the Solar System, specifically Mars who, as you know if you were a member of our fraternity/sorority in ought-three, was putting on his best show in millennia.

I’d obtained some killer shots of the Angry Red Planet with the C11 and C8, but one night when I was done doing that, I decided to give the Konus a shot at Barsoom. The result, as you can see, wasn’t that bad. The problem was not the optics, but, as when observing planets visually, the lack of focal length. Even on nights of so-so seeing I was shooting at at least 6000-mm with the C8. Getting that kind of image scale with the Konus meant stacking Barlows, further stressing the subpar focuser, and still not getting the image scale I was after. But the optics were good, and if I’d had a better focuser and a 5x Powermate, I reckon the 8 coulda done a job at least competitive with the C8 if not better.

It seemed like a long slog, but I finally had all the observing legwork for the book done, and not too long after that The Urban Astronomer’s Guide was off to the publisher. What would happen to the Konus/Synta? I didn’t foresee selling it; it was too cheap to get much money out of, and its weight and size would have made it an expensive pain to ship. But would I continue to use it for something? I intended to. B-U-T. My C8, now mounted on a go-to Synta/Celestron CG5 could, with a focal reducer, mostly duplicate the views of the Konus. Oh, occasionally I’d drag my Old Yeller out back, on those evenings when I wanted a little horsepower and didn’t want to fool with go-to computers. To be honest, even on those nights, I usually left the Curious Yellow OTA inside and just slapped a C8 OTA on the Konus EQ4. Steadier, easier to carry out and in. Most of the time I didn’t even fool with a C8 for the backyard. My little StarBlast got more use in the backyard than either a C8 or the Konus. A lot more. Uncle Rod is lazy.

I was using the Konus so little that I eventually found a new home for its EQ4 GEM. My ATM buddy, Pat Rochford, had just finished an 8-inch mirror of short focal length, and needed a mount for the OTA. I handed over the EQ4 with a couple of caveats about the tripod. I needn’t have worried. Pat soon discarded that abortion and had fabricated a much nicer and nicer looking wooden tripod. Old Yeller’s OTA was relegated to Chaos Manor South’s Upstairs Equipment Vault. I used the tube on the CG5 a time or two, but it was a bit heavy and long for that mount, even given a tripod worlds better than that of the Konus model. And, again, why bother? The C8 provided similar views with a focal reducer and was better suited for the CG5.

And so it went till one day when I was over at Pat’s admiring his finished 8-inch Newt. Pat ain’t just an ATM, he is an innovator. His design for his fast 8-inch was radical and practical. In order to spare the EQ4 of too much of a payload burden, he’d built a minimalist truss tube OTA: three (non removable) tubes, a lightweight mirror box, and an e’en lighter weight upper cage. I must have gushed about the new scope a lot, since Pat asked if I’d like him to build a new OTA for my Konus optics. That might encourage me to use it on my CG5. I was enthusiastic about the idea, and soon Pat was at work. In addition to fabricating a new primary cell, we (well, Pat did; I watched) used a much better focuser, one of JMI’s RCF Crayfords. I encouraged Pat to get as radical as he wanted to with my 8, and that he did. As you can see in the image, the upper cage (for want of better words) is hardly there at all. One ring, a plastic light baffle, and a mount for the focuser. Pat reused the primary mirror, secondary mirror, secondary holder, spider, the 50-mm finder, and some hardware (mostly the Vixen-type dovetail).

Alas, I still didn’t use this now-beautiful scope. Why? Same old - same old: too much trouble to tote into the backyard and not much reason to haul it to a dark site in lieu of a C8. Pat slowly came to feel the same way about his rig. Before I knew it, he’d converted his 8-inch into a low slung Dob, and wanted to know if I’d like him to do the same for mine. “Hail yeah.” Wasn’t much reason to keep the scope as she was. ‘Bout all she was doing was performing doorstop duties upstairs.

What’s special about New Yeller? First of all, she is light. When I arrived at Pat’s to pick her up and take first light, we needed to move the scope from its original set up position in the yard in hopes of getting Saturn into the field (the new scope curse did bite this time, with Saturn the only thing available through a sucker hole in the east). Pat said, “Move it where you want it; it’s easy.” I grabbed the scope by both handles, lifted it, and nearly heaved it into the air because I was not prepared for just how light it really was. Hell, it didn’t seem much heavier than my StarBlast + StarBlast Stand. Another wonderful surprise was the scope’s extra-buttery motions. The bearings ride on the traditional Ebony Star Formica and Teflon and provide the smooth action Dob users crave. Even more wonderful was the Dob’s lack of balance issues despite its short, light tube. Pat is a firm believer in large altitude bearings, and he’d not just gone “big” but “wide” this time. Removing even a sizeable eyepiece like an Ethos doesn’t send the scope tube up on a hunt for the zenith.

Obviously minimalism does come at a price. The secondary mirror is out there in the open and not much protected from dew, always a concern down here in the swamp. That problem was cured easily enough by the addition of a secondary heater we fashioned out of a .965 Kendrick finder eyepiece heater strip I had laying around the Old Manse. There was also the question of where to put a finder and what kind of a finder to put on the scope. While the balance on this Dob is not at all critical, we still didn’t want to add too much weight up top. Out went the 50-mm finderscope. Even a TELRAD seemed too big, heavy, and clunky-looking. The solution was a Rigel Quikfinder, which is more in keeping with Pat’s design, both appearance and weight-wise. I don’t like its reticle quite as much as I do the one on the TELRAD, but almost.

A final surprise, though it shouldn’t have been, was the views the Konus optics yielded. At the highest power we could muster, Saturn’s disk was wonderfully detailed, the near-edge-on rings showed their ring nature clearly, and four little Moons lined up in a striking row east and west of the planet. What else was obvious? My much-loved StarBlast would have a real competitor in the grab ‘n go game. New Yeller is not much more of a strain to get into the backyard. When I want major-time detail on the Moon or a planet, or more than a glance at a deep sky object, there is going to be no contest. New Yeller is gonna blow the doors off the Little Feller.

In addition to its light weight, easy motions, non-fussy balance, and good optics this is also one of the most—If not the most—beautiful Dobsonians I have ever seen. When I toted her home and set her up in the livin’ room, Miss Dorothy went one step further, opining that this was the most beautiful telescope of any kind she had ever seen. I used to think Rick Singmaster’s famous 7-inch Oak Classic Dobsonians was the winners of the small Dob beauty contest, but Pat’s creation just beats the pants off ‘em.

So the reborn GEM Newtonian just didn’t pan out for me? I reckon not. I love my C8s. They are more compact and more versatile than an EQ Newt. I don’t have to rotate the whole consarned tube as I slew across the sky. The SCT is far more practical for any kind of imaging. And yet, and yet… Six years later, Orion is still offering a GEM 8-inch for a still modest price (649 without drives, but with a much better tripod than what the Konus had). Not a bad buy for someone who wants trackin’ so they can maybe get their feet wet with imaging and sketch to their heart’s content. Me? I’ll always have a soft spot in me little heart for them hulking and impressive (looking) GEM Newts, but it’s a fondness I’ll prob’ly henceforth choose to experience only in fond rose-glassed reverie.

Comments:
Wow, it did turn out beautiful. Pat is to be commended for his work.
My grandnephew thinks now that the 8" Orion XTi I got him is too big. So I am going to trade him a 4" Achro for it. Then I will see about converting it to something like yours. To that end I lifted your picture of it as it is now. It really is sweet.
One question, sir. What are the truss poles made of? Are they metal or wood dowel pins? Thanks again, great story. I often wonder how you find the time.
Doug
 
Hi Doug:

They are aluminum tubing (painted)...most hardware stores have similar.
 
Wow that was quite astounding to read.INFORMATIVE. Great work.I hate refractors , they give me road rage !!! I help alot of people in email from my blog picking out their first telescope depending on their budget etc. so far 38 people have written me frustrated with their little refractors that a pro at the telescope store sold them.
 
Rod, just an FYI but the link in the article to the book on Amazon takes you to the Kindle edition, not the paperback.

Looking forward to getting mine (paperback version that is).
 
Geez, Louise...I didn't know it was out in Kindle. Welcome to the 21st century, I reckon. Thanks for your sharp eyes.
 
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