Saturday, January 28, 2023


Issue 588: Uncle Rod and the Rescue Telescope


Back in her natural element...
Sounds like the title of the next Disney Channel animated series, don’t it, muchachos? I bet you thought Unk would be writing about the comet nine-day-wonder, Comet 2022/E2 ZTF, dincha? That will come. Up to now it’s been too cloudy or too cold and the comet has been rising way too late (early, that is) for your lazy Uncle. Today, the subject is Uncle Rod’s latest rescue telescope.

What in pea turkey is a rescue telescope?! A “rescue telescope” is most often a modern iteration of the Department Store Telescope that has fallen on hard times, has fallen about as far as a telescope can fall. Maybe it began as a Christmas or birthday present to a young person or an impulse buy by an adult. It was quickly found to be deficient in that its images didn’t rival those of the Hubble Space Telescope. It was under the stars a few times and brought its owner a pretty Moon but was soon found to be Too Much Trouble. The briefly loved scope, its wonderfully gaudy box long discarded, finds its way into a closet where it sits bereft of starlight for a long, weary time.  

The scope’s descent doesn’t stop there. Sooner or later, it becomes an annoyance, taking up room in that closet, crashing to the floor every time the owner retrieves their galoshes, and making a general nuisance of itself. Sometimes it’s given away and the story thus far repeats itself. Most often, it is put on the curb, to be either plucked by the trash pickers or sent to its final demise. Sometimes it gets lucky, though; the owner donates it to a charity thrift store and sometimes, just sometimes, someone comes along and gives the poor thing a second chance.

Anyhoo, one recent Thursday evening, Unk found himself arriving a little early for a radio club meeting held at a Goodwill Community Center adjacent to a Goodwill Thrift Store. The previous week I’d found a Simpson 260 multimeter in there for the grand sum of nine dollars. With a little time on my hands, I wanted to see if I might get lucky again and headed for the back of the store where the electronics are kept…but didn’t get that far.

At first Unk thought he was going crazy(er). I seemed to be hearing a plaintive little voice. A little female voice: “HELP ME, UNCLE ROD! YOU’RE MY ONLY HOPE!  My puzzlement turned to understanding when I spotted a 4.5-inch Newtonian sitting beside the aisle on her spindly tripod.

“Hello, little one. How long have you been here?”

Oh, Unk, I’ve been here the longest old time!”

“Well, let’s have a look at you.” What was before me was a current Department Store Telescope (DST). You thought they were gone? No, they, the telescopes in-between toys and genuinely serious but inexpensive scopes like the Orion Starblast, are still with us.  They are still sold in actual department stores, but also in hobby shops and, of course, online. Most of them are the ubiquitous 114mm (4.5 inch) Newtonians, 60mm refractors being less numerous than they once were.

How is the current crop compared to those of yore, like the famous Tasco 11-TE? Compared to 60s – 70s DSTs, they are mostly worse. The big and debilitating problem is their mounts are shakier (and they weren’t the Rock of Gibraltar way back when), wooden tripods having given way to extruded aluminum jobs barely adequate for low power. Eyepieces, however, are definitely much better now. Most are fairly good 1.25-inch oculars that blow the doors off the .965-inch horrors of the past. Finders have improved, too, red dot jobs having displaced small-aperture, stopped-down optical finders or the dreadful “reflex” finders Jason-branded scopes once sported.

That glorious box promising wonders...
“But how about the optics?”  They are generally well-made, BUT… Back in the glorious day, 114mm reflectors from Japan, and, later on, 114mm reflectors from China, had spherical primary mirrors, yeah. But they also had focal ratios of f/8. At f/8, a 4-inch spherical mirror is quite close to ¼-wave of wavefront error and can perform very well. Alas, most DSTs now possess f/5 – f/6 spherical mirrors. At that focal ratio they approach a half-wave of error. Not horrid, perhaps, but worse. Why the move away from f/8? I guess f/5 tubes may be cheaper to produce and cause less stress for today’s pitiful DST mounts.

Looking at the waif before me, I noted the label on her (plastic) focuser read, “Celestron 114-AZ SR D=114, F=600, F=5.2, MADE IN CHINA.” I almost walked on, knowing the limitation that would impose given the spherical mirror I knew this little girl would have. But I didn’t. I’ve seen Celestron 130mm scopes with spherical mirrors do OK on the Moon and other subjects at similar focal lengths, so why not?

I’ve also gotta admit the Celestron tugged at my heart strings, looking sad and pitiful with her banged-up steel tube tarted-up with paint to make it look like carbon fiber.  And I am always on the lookout for scopes to pass on to enthusiastic young undergraduate astronomy students. Also, there was the price tag on her, “$19.99.” Finally, paraphrasing Charlie Brown, I said out loud, “Besides, I think this little telescope needs me.”

The Celestron, who told me her name was “Tanya,” begged to be taken home: “Uncle Rod, my red dot finder alone is worth 20 bucks. PLEASE GET ME OUTA THIS PLACE!” I took a look at her primary, which appeared bright and clean, and surveyed the rest of her. She looked complete with a couple of cheap Plössls, one in her focuser and one in her little eyepiece tray. Well, almost complete; her aperture cover was long gone. I scooped the girl up and headed to the checkout, “Oh, thank you, Rod! I know we’ll be great friends!”

A hard-knock life.
Back home after the radio club meeting, Miss Dorothy wasn’t too surprised to see me come in with yet another wayward scope in my arms. She was rather surprised by the 20-buck price, though.  You know, so was I. Sitting in the kitchen, Tanya looked far better than she had under the merciless fluorescents at the Goodwill store. Next step was seeing precisely what was up with the girl.

My initial examination showed one of the two eyepiece locking screws was jammed. It was so tight I had to resort to (carefully) unscrewing it with a pair of vice-grips. To my surprise, it wasn’t cross-threaded and stripped, just screwed down awful tight. When it was loose, I was able to extract the 9.7mm Plössl (both eyepieces being Celestron’s extra-cheap ones with metal barrels but plastic bodies) and examine the secondary mirror. A look in the now empty focuser showed several big blemishes on it. Might just be dirt or might be damage to the coating—there is no telling what a kid who got a telescope instead of the battery-powered scooter they really wanted will do to torture the poor thing.

Otherwise, it was clear Tanya had indeed led that proverbial hard-knock life. There were several small dents and dings on the tube, and something—who knows what?—had been sprayed on it here and there. There was also plenty of the dreaded Chinese glue-grease (apparently made of ground-up weasels), which had migrated from focuser, to tube, to mount, to tripod with the aid of young fingers.

There was a crescent Moon in the sky, so naturally I got little Tanya into the backyard for a look. Before doing that, I gave both her oculars a good cleaning—they were filthy. How was that Moon? Not bad. It was sharp enough given the obvious mis-collimation of the un-cooled-down optics, poor seeing, and the only fair quality of the eyepiece (these plastic-bodied Plössls are used on many of Celestron’s/SkyWatcher’s lower-priced scopes). Anyhow, Tanya did well enough I declared she had possibilities and told her we’d get her cleaned up in the morning.

That morning, if not too early that morning, I set off to obtain something I knew I’d need, paper-reinforcers to make a center dot for her primary mirror so I could collimate her. To my astonishment, Publix had none. Neither did Walgreens. Nor did the Walmart food store. I finally turned some up at CVS drugs. Is there a paper-ass*&^% shortage or something?

Back home, out in the Batcave, my radio shack cum-workshop of the telescopes, I thought my first task would to be to clean the secondary. As you can see in the image below, the secondary’s spider is an integral part of the plastic fore-end of the tube, as is the finder mount.  I spotted a few Philips-head screws and removed those. It was apparent the focuser would also have to be removed to get the plastic section loose.

I did that, which was just as much of a pain as removing the other screws, since all were held in place by tiny nuts and Unk couldn’t get his fingers very far into the tube due to the thick plastic spider vanes. Finally, all screws were removed, but the plastic assembly still refused to budge. It was pretty obviously glued as well as screwed into place. One of the problems with this and similar little scopes is they are not made to be maintained—they are like Chinese puzzle boxes.

Ready for collimation.
Rather than try to defeat the glue, I decided I’d clean the secondary in situ. With the focuser removed, the hole in the tube was large enough to allow that. To my surprise, gentle cleaning took care of the multiple spots of dirt or whatever (it almost looked as if—horrors—someone had spat on the secondary!). It was now clean and pretty, and I was able (with some difficulty) to get the focuser back in place.

Next up was collimation, but to do that, I’d have to center-dot the mirror. I was surprised not to see a dot on the primary. Even Synta's (the parent corporation whose brands include Celestron and SkyWatcher) lower-priced “amateur astronomy class” scopes like the aforementioned Starblast have ‘em. I suppose they don’t bother with those like the 114AZ bound for hobby/toy/department stores.

How do you center dot a mirror that ain’t got one? Grab a compass, draw a circle the same diameter as the primary on a piece o’ paper, fold it into quarters, snip off the apex of the cone formed, unfold it, place it on the mirror, and carefully make a dot on the primary through the hole. Center the paper reinforcer on the dot. If you’re as OCD as Unk, you’ll then take a Q-tip moistened with alcohol and gently remove the sharpie mark.

I collimated the little thing using the Celestron combo sight-tube/Cheshire I’ve had for years. If you want to know how to do Newtonian collimation, see my blog entry on the subject. Having done a Newtonian fairly recently, I did not have to reference my own article. Denouement? Secondary and primary were both off a considerable amount but were easy enough to get “in” in just a few minutes.

Done for the moment with the OTA, it was time to see what I could do to improve the mount. The azimuth axis had a healthy dollop of that glue-grease. So much of the viscous stuff the tube tended to continue moving in azimuth when I stopped pushing it. A little of my favorite cure, DeOxit, and the application of some Blaster synthetic lube freed up the motion quite a bit. There was only so much I could do, since the azimuth axis was pressed into place and would have been difficult or impossible to remove, but it was better.

Wasn’t a whole lot to be done for the altitude axis. A little lube in the trunnions and that was it. The altitude slow-motion arm (talk about a blast from the distant past) did not need any attention.  Finally, I used some 99% isopropyl alcohol, DeOxit, and WD-40 to banish the many patches of weasel grease on mount and tripod.

The spider is part of the end assembly of the tube. 
I then returned tube to mount and proceeded to see if I could do sumpin about the stiff, wobbly plastic focuser. Replacing its glue-grease with synthetic lube helped. I was also able to make its motion easier by adjusting the two screws on the rack and pinion focuser’s underside. However, it was clear the focus tube would always be floppy. Like the similar plastic focuser SkyWatcher uses on its “tabletop” Dobsonians, there is no lock screw, and mechanical tolerances are large. I thought if the scope performed halfway decently, I’d think about some Teflon shims or something.

Last thing? I tried to make poor Tanya pretty again and was partially successful. I was, with mucho scrubbing and application of Pledge furniture polish, able to remove most of the nasty-looking spots on the OTA. Oh, she’ll never look like she did the day excited hands pulled her out of her Technicolor box, but, yeah, she looked much better. I picked her up, cradled her in my arms, and took her to the backyard to acclimatize ahead of darkness. You know what? The little scope positively glowed sitting there.

While waiting, I thought I’d learn a little something about Missy. It turns out she is a currently sold scope retailing for about 100 bucks at—fittingly—Kohl’s department store. Seems to me I may even have seen a 114AZ in the Kohl’s up the street last Christmas.  I also solved a mystery:  what the “SR” in the telescope’s model number means. The 114AZ SR is smartphone ready. What does that mean? As she came from the factory, the scope was furnished with a little cell phone mount so you could take pictures through the eyepiece. That mount, which apparently involved rubber bands, was not with Tanya at Goodwill, and had no doubt gone missing along with the aperture cover (and a pack-in DVD of the Starry Night software) long ago.

I sat and waited for it to get dark enough. But you know Unk; I got “go” fever: “Hail, it’s dark enough to look at the Moon.” And it was. The difference between bedraggled Tanya the previous night, and tonight’s prom-queen Tanya was more than palpable. The just before first quarter Moon was simply scrumptious.

At 60x with her so-so (or maybe not so so-so) 10mm eyepiece, Selene was a thing of wonder. With darkness having arrived, I thought I’d push her a small amount. I plucked one of Celestron’s slightly better Plössls, a 6mm, out of its case to see what she could do with 100x, a more practical magnification for observing the Solar System. With a little more power, the trio of craters, Theophillus, Cyrillus, and Catharina, was simply breathtaking.

Was the wee scope perfect? Hardly. Even at “just” 100x, there began to be problems. Not with the optics, but with the mount. At that modest magnification, it began to border on unusable. Oh, I could get the telescope in focus, but it was quite shaky and I had to exercise a light touch. Combine that shakiness with the shallow depth of focus of its fast focal ratio, and a scope like this challenges the very people it is supposedly designed to serve, children and beginners. However, it is definitely at least OK with the two supplied eyepieces, which furnish 23x and 60x.

Looking and feeling much better!
Maybe the biggest surprise of the night was ol’ Jupe. He is not an easy object for small telescopes, really, and is where many cheap ones fall completely apart. “Is that Jupiter or a custard pie?”  With the 6mm in place we headed for the King. I didn’t expect much and was frankly amazed. The four Galileans were sharp, sure, but the big deal was I was seeing banding, plenty of it, on the disk, and maybe the even Great Red Spot, too (I wasn’t sure whether it was visible or not; I checked later and it was).

While the sky was beginning to haze over, as it had been since sundown, I just had to take a look at M42. The Trapezium was easy and there was as much nebulosity on view as I’d expect any 4-inch to show on a less-than-average night. Oh, we made a few other stops as well. The ET Cluster, NGC 457 was pretty if more subdued than on a good evening. But we ended on Luna again. I couldn’t stop marveling what at what this formerly debased little telescope was showing me.

Frankly, I was thrilled I’d been able to bring this sad little refugee back to life. Unfortunately, while the sky wasn’t looking any worse than it had, and the winter stars were glittering bravely in the haze, the one thing that always indicates it is time for Unk to end an observing run occurred. My feet got cold. When that happens, it is end of story, game over, zip up your fly. I picked the little scope up, deposited her in the Batcave (her aperture covered with a shower cap), and was inside watching television with the cats in just a few minutes.

When the time is right, yes, Tanya will undoubtedly go to some deserving young person, but till then, yeah, it’s just as she said; we’re going to be great friends.


There is nothing worse than a telescope that is relegated to the basement or closet and cannot gather any photons at all.

Beautiful story Unk. I recall years ago finally sending my first 60mm Tasco refractor, and later my 4.5 inch Tasco equatorial off into the unknown at a school rummage sale. I hope they found new lives like yours.
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