Jim L

Around the winter holidays a warehouse chain store in the U.S. and Canadian sold these Celestron Omni 102 AZ scopes with tripod, diagonal, and two eyepieces for around $159 USD. We already have a longer focal ratio 102 mm Celestron, but at that price my wife couldn’t resist bringing one home to play with. The mount and correct image diagonal went to the ST80 in the first post, and the Omni 102 AZ now rests on the altaz mount and Manfrotto 055 tripod in the photo above, or on a Sky-Watcher AZ GTi goto mount when tracking is desired. Both scopes and mounts are much happier in their respective positions. The scope is surprisingly light and well balanced, and I can pick it up easily with one hand. This is in part because the dovetail bar is attached directly to the optical tube, eliminating the weight of tube rings. Everything else on the OTA is sensibly built to be strong and robust enough, but no more. Mounted and ready for observing with diagonal and eyepiece, I can lift the entire kit with one finger. I can’t say that about my other 4” scopes. I was pleasantly surprised that the all metal lens cell threads directly onto the steel optical tube. Many inexpensive achro refractors have plastic lens cells that are held in place on the optical tube with sheet metal screws, and that can make obtaining and maintaining collimation challenging. Collimation on this scope is near perfect, and in the absence of some unfortunate accident I expect it will remain that way indefinitely. I picked up a used 2” Orion dielectric diagonal for $50, and with it and the right eyepiece this 102 mm f/6.5 scope is capable of a 4° true field of view. The optics of this moderately fast scope are marvelous, and the views they reveal are surprisingly sharp and bright. The Trapezium within Orions Nebula shows beautifully, the Pleiades and Andromeda can be easily enjoyed in their entirety framed within a huge expanse of black space, and my wife and I observed bands in Saturn’s disk and the Cassini Division In Saturn’s rings several months after Saturn’s opposition. The optics really are astounding good for a 102 mm 660 mm focal length crown and flint achro. This scope has largely supplanted my ST80 as the scope I grab to check observing conditions from my back yard. It’s nearly as light and handy as the ST80, but with much more grasp and far more capable optics. These cold and windy winter nights it’s probably my most used scope because it’s so easy to move in and out of the house for a quick look at the night sky, and the views through it are so satisfying.

Got me, hook, line, and sinker!

I just remembered that the barrels of the Sv215 zoom and Nagler 3-6mm zoom eyepieces are long enough to make contact with the optical components of several 1.25” diagonals, including the Takahashi prism diagonal, the Baader T-2 Zeiss spec prism diagonal, and the Baader T-2 BBHS mirror diagonal. As far as I can tell none of the diagonals I just mentioned have an effective safety stop within the eyepiece holder tube, and the SvBony and TeleVue zoom eyepieces may hit glass if measures aren’t taken to prevent contact. There are probably other diagonals that are similarly unprotected. Parafocal rings can be installed on the zoom eyepiece barrels and are an inexpensive and effective solution to this potentially expensive problem.

Speaking of ST80 scopes, episode #312 of The Actual Astronomy Podcast includes an audio observation of the Sunflower Galaxy (M63) made by Phill using an ST80. Phill, who is a regular contributor to the Actual Astronomy Podcast, began his observation of M63 using a 41mm eyepiece, then a 30mm, and eventually settled on a 15mm ultra wide eyepiece which at 26.7x magnification gave him his best view of the magnitude 8.52 galaxy. Phill reported that he could detect “…the nucleus, and the mottled textured diffusion of light in an elliptical shape.”

I’ve often wondered about the Meade ETX series of scopes. They must have been very popular in their day and I see them up for sale quite regularly. It’s interesting that the smaller scopes of the series are refractors and the larger are reflectors. I haven’t looked through one yet, but I’d sure like to.

While most everyone appreciates a fine optical instrument with hand figured crystal lenses, a feathery two speed focuser, and a precision machined lens cell, there’s a charm, an exuberance, a charisma, inherent in a cheap and cheerful crown and flint achromat that’s perhaps in some way missing from the more serious and staid exotic glass apochromats. Even the words “crown and flint” evoke a yeoman’s silent dedication to the task at hand that’s free of either excuses or braggadocio. For most of us these simple but often surprisingly capable scopes gave us our first views of the rings of Saturn and moons of Jupiter. It’s how and why we got here in the first place. So, and in the spirit of friendship and camaraderie, let’s celebrate our own crown and flint achros, one’s we own now, and those in our past. Tell us their stories, where they’re from, where they are now. Let’s save our fancy scopes for some other time. This is for the cheap glass lenses, cast single speed focusers, Phillips head screws, and metal tubes we love and sometimes hate, but mostly love. I’ll start with the little orphaned ST80 above. It was free, having been abandoned by its former owner whom I suspect was frustrated with its basic equatorial mount, and it now rests on a cheap aluminum tripod and mount robbed from a Celestron Omni AZ 102. I attached a pair of peep sights made from aluminum furniture corner reinforcers to aid in aiming the scope, though they work better during the day than at night. I’ve got it parked at my rear window pointed at a bird feeder in the back yard, but it will soon find a new home with a budding young amateur astronomer I hope to gift it to at an upcoming local Star party. I think it’ll make him a great first scope. Now let’s see yours…

Baader sells an optical monomer film that is an uncoated version of their solar film which they call TurboFilm, and which they claim to be optically equal to a 1/10 wave plane parallel optical window. Perhaps a frame to hold the film and that could slip into a window opening would be a worthwhile step in the right direction. Here’s a link: https://www.baader-planetarium.com/en/turbofilm-127-x-51-cm-nd-01.html

I think you’ll enjoy it. I had my own Sv215 3-8mm zoom out last evening looking at the moon through it and a 50mm f/5 achro doublet. Conditions were so-so, with high thin clouds and high winds conspiring against good seeing, but the little scope on its photo tripod is so easy to deploy it often goes out when I wouldn’t commit to taking out a larger scope. The views through the scope are always surprisingly good for its quite modest aperture and last night was no exception. I found the 5mm setting on the zoom to be good at the time, and remembering I have a newish 5mm T6 Nagler thought a quick and dirty non-scientific comparison might be fun. I picked the particularly sharp ridge top of a convenient crater near the terminator as my target of comparison. Swapping the two eyepieces back and forth I was surprised that on and near center the Sv215 zoom was every bit as sharp and crisp as the Nagler, and that it was also perhaps a bit brighter. I swapped enough times to be pretty sure of my observations, and while somewhere in the back of my mind I hoped that the Nagler would prove superior, at that time, for that target, through that scope, and under those conditions, it wasn’t. Long story short, the Sv215 zoom is a pretty good short focal length zoom eyepiece, and especially so for the price. Along with a Sv135 7-21mm zoom and a 32mm Plössl, the three eyepieces make a simple, compact, and versatile combination for a fast refractor.

There is a small cohort of posters at CN that has apparently made damaging StellarVue and Vic Maris their mission in life. Though not a fan of StellarVue, Paul isn’t one of that bunch, and his bench test of a single 180 mm StellarVue triplet was made in good faith. Paul found the scope was almost perfectly corrected in red, and less so in green and blue. StellarVue refunded the owner the full cost of the scope, including shipping, and I’m sure they’ll perform a detailed analysis to determine what went awry. One possibility is that one of the lens elements shifts in its cell, which is supported by the owners observation that sometimes he could see what looked like atmosphere dispersion, while other evenings he could not. That would seem to suggest atmospheric dispersion or a inconsistently located lens element. The owner of the tested scope observed that the belts in Saturn were more apparent and easier to see in the StellarVue than in his 6” IZOS refractor or his 10” Zambuto reflector, that the Cassini Division was a wide, etched, division, and that in the thinnest part of the rings the division remained very apparent as a thin line. The owner made similar favorable observations of Jupiter, Mars, and Sirius and its companion. I’m not an imager, but photos I’ve seen taken through a SVX180T look very nice to me. The large majority of StellarVue’s sales is to imagers. Concerning the use of a Zygo interferometer set up in red, I know little about it, other than it doesn’t necessarily have to be problematic as long as green and blue follow along for the ride, and that at least some optics made for the aerospace and defense industries must be certified in red by contract. StellarVue uses their interferometer as a tool to identify and map areas on a lenses for further figuring. Where does that leave us? Beyond the abundant nonsense from the CN test thread, including a ludicrous bit concerning whether “another venue” referred to the law courts or to FaceBook, one has to decide whether a group of posters who have never made a telescope, much less one for sale to the public, that on the basis of one test of one scope that may have a faulty lens cell, have somehow caught a very successful company that has sold telescopes for two decades and has hand figured their own optics for the past ten years in a mistake of such magnitude that the company can’t and won’t survive. William of Ockham might have thought the number of assumptions required to come to that conclusion excessive. My own take is that there’s a distinct possibility that the lens cell from the tested scope may be faulty and allow one or more elements to shift. We may hear back from StellarVue in a couple of months after they’ve returned from NEAF, or we may never know. As to Vic Maris and the rest of the crew at StellarVue, I suspect they are capable of designing and building a telescope that performs well and to the expectations of their customers as evidenced by their long history doing so. Whatever the outcome of the StellarVue drama one thing is certain, there is a partisan camp of insufferable whistles with an ax to grind against Vic Maris and StellarVue and in a way that seems antithetical to the spirit of amateur astronomy. The pity is that there is an even larger audience that without much in the way of reason or reflection are all too happy to tag along for the ride. It’s probably best they stay over there.

Ernest, of the Astro Talks website, does quite detailed reviews of optical gear, including zoom eyepieces. The website is in Russian, and so for many it will need to be translated, but Googles’s translation algorithm does a pretty decent job. Here’s a link to some of the zoom eyepiece reviews: https://astro--talks-ru.translate.goog/forum/viewtopic.php?t=4585&_x_tr_sl=ru&_x_tr_tl=en&_x_tr_hl=en-US&_x_tr_pto=wapp&_x_tr_sch=http

Podcast #303 of The Actual Astronomy Podcast is largely devoted to the history of, and discussion about, 4” Takahashi telescopes. For those who don’t have a podcast app already loaded, the link below should allow you to listen in: https://actualastronomy.podbean.com/

Malcolm, I hope you don’t mind me borrowing your and Robinson’s quotes from time to time. There are certainly many equipment related discussions where it would be handy to reflect on the perils of confirmation bias, and particularly so when making recommendations to beginners like myself.

Inspired by classic British trials cars. With its Torsen rear end, 1.6L of fury in the front end, and the weight of a half dozen apos and counterweights in the trunk it’s almost unstoppable. Some observing sites require more commitment to reach than others.

Not the big, black, Celestron, but the little guy in the case down below… 50mm f/5 Astro Tech finder, SvBony 7-21 zoom, Manfrotto 190 tripod, Manfrotto 128LP fluid head. Fits in a child’s lunch box, one finger carry and splits Castor at 36x magnification.

And, the telescope transport vehicle…

I can feel the barometric pressure drop from here!

The fact that the label says it was made in the U.S.A. suggests it was made some time ago, as later versions were and continue to be made in China. The basic formula remained the same, however, and so what applies to the 9.25” Celestron also applies to your Orion scope. Given its age chances are it would benefit from a careful collimation, the instructions for which are in the previously linked manual, and which the many Schmidt-Cassegrain owners and fans here can also help you with. Well collimated it’s probably an excellent and very capable telescope. That was a very nice and generous gift from your friend.

Orion’s 9.25” Schmidt-Cassegrain was made by Celestron. Here’s a manual to get you started: https://usermanual.wiki/Orion/OrionSchmidtCassegrainTelescopes8925And11UsersManual497971.1232587163.pdf

John, I don’t know whether the Kenair Air Duster will provide a more or less powerful jet than the rechargeable Reesibi R3 duster I linked, but the R3 will provide a continuous strong and high volume jet of air of consistent force over a prolonged period of time. In contrast, after two or three short bursts from a can, the can cools and the jet force drops dramatically; and you can forget about a continuous blast from a can. I stopped using a can the first time one left a film deposit on my telescope objective. I moved to a large Giottos hand air blaster and while it never left a film it left something to be desired as far as power and volume were controlled. Then I read a post from Don Pensack where he said that rechargeable air dusters were much more effective than the alternatives, and that was enough to convince me. I’ve only had mine for a couple of days, but as usual, Don was right. As to whether the less expensive rechargeable duster is as good or even better than the Reesibi duster, your guess is as good as mine, but I’m very impressed with my Reesibi R3.

I purchased this rechargeable air dusted a few days ago: https://www.amazon.co.uk/Reesibi-Strongest-50000-90000-Compressed-Rechargeable/dp/B09QX59BNK?ref_=ast_sto_dp&th=1 I chose this particular model over it’s competitors because it has a brushless motor. Will the brushless motor make a difference in performance or durability? I’ve no idea but I figure it can’t hurt and here in the States it’s the same price as the bushed motor models. My region of California is semi-arid and that means lots of dust. The rechargeable duster works brilliantly for removing that dust and is far superior to both the squeeze bulb dusters and the canned air. It moves a lot of high velocity air without the potential danger of blasting your optics with propellant or other undesirable compounds, and it’s far more powerful than any bulb duster. My only regret is not having got one earlier.

You can rotate the camera to see what effect that has on the location of the defect. If the defect follows the orientation of the camera, the problem is with the camera. Same with the filter and anything else in your optical system. Many spotting scopes are sealed, Astro telescopes are not. Dew and accumulating dust and other debris is inevitable, but you can take steps to minimize their effect. Dew heaters help, as does keeping the objective caped when not in use and blowing it off after use. Good luck!