Jim L

It’s not Monica we should be concerned about!

I doubt there’s a manufacturer that tests their scopes more thoroughly or watches quality control more carefully than StellarVue. So what happened to that SVX180? I had a lengthy conversation with Vic Maris in which he thought that scope may have had an optical element rocking in its cell. He didn’t know for sure since at that time he hadn’t received the scope back, but he said that as tested by a Paul it was far below their standard. One variable not mentioned are the perils of shipping from the West Coast to the East, which has no doubt been the downfall of many a fine instrument. Having the luxury of living only 90 miles from StellarVue I drove to their shop to pick up my own scope so that I could be assured that it’s optics would arrive in the condition in which it was certified. Perhaps the SVX180 had gotten more of its share of wacks courtesy of FedX; who knows? On the possibility that the issue was caused at his end, however, Vic said he was returning to first principals and examining his entire operation from start to finish, including calling in a technician from Zygo to examine their interferometer. The end result, I expect, will be very positive for both StellarVue and its customers. As to other manufacturers, I don’t know the lengths to which they go to manufacture and deliver quality scopes, but the comprehensive AiryLab test results provide a window into what is in the hands of some of their owners. Here are the five Astro Physics StarFire130 AiryLabs has published: https://www.airylab.com/contenu/mesures/astro/rapport 2011-05002-public.pdf https://www.airylab.com/contenu/mesures/astro/rapport 2011-05003-public.pdf https://www.airylab.com/contenu/mesures/astro/rapport 2013-15001-a.pdf https://www.airylab.com/contenu/mesures/astro/rapport 2012-46001-a.pdf https://www.airylab.com/contenu/mesures/astro/rapport 2014-09002-a.pdf TEC is often discussed here, so here are the two TEC 110FC results published by AiryLab: https://www.airylab.com/contenu/mesures/astro/rapport 2014-33001-a.pdf https://www.airylab.com/contenu/mesures/astro/rapport 2014-33001-a.pdf I’m not sure what to say about those results except that perhaps their owner’s delivery service is even worse than ours here in the States. Significantly, astronomically, worse. Here’s a visual from one of the TEC tests: For those readers who don’t wish to go through the trouble of reviewing the tests I don’t expect you would find many of the results of optical quality either superior or consistent, and your assumptions about the performance of some of your favorite scope makers might be challenged. There are dozens of additional test results published by AiryLab on their website, but be advised that if the test link doesn’t work you will have to replace “net” in the link with “com” after “airylab.” Here’s a link to AiryLab: https://airylab.com/astronomy-test-reports/ Some of the published test results are quite good, others much less so, but it’s difficult to find any sign of consistency. The difference, it appears, is that when a StellarVue scope tests poorly they’re flayed before being tied to a stake and burned, and when a scope from another top maker tests equally poorly or worse, the subject is swept under the carpet to be ignored until forgotten. Then StellarVue is damned with faint praise as the maker that is almost as good, and can be as good if they just try harder, but that are not quite there yet. StellarVue is every bit as good right now, I expect they will try harder, and if the test results linked are any indication perhaps other makers should try harder as well. One lesson that’s finally sinked in over my 67 years is that when I’m resolutely positive that someone who absolutely should know better has screwed up majestically, when my thoughts go to, “what could they possibly have been thinking…. ”, a deeper examination of the facts almost always shows that it was I who did not adequately understand the subject. I think a bit of that trap creeps into every discussion about StellarVue scopes. Mark Twain’s observation that, “What gets us into trouble is not what we don’t know. It’s what we know for sure that just ain’t so.” should probably be kept in mind in any discussion about StellarVue.

Louis, in the 10” size I’m interested in the Apertura costs $950 and is on back-order, while the SkyLine costs $900 and is in stock. The only difference I’m able to find is the Apertura includes a 35mm extension and the SkyLine does not. https://www.highpointscientific.com/brands/apertura/apertura-ad10-10inch-dobsonian-telescope-ad10?rfsn=6699648.e10fc93&utm_source=bing&utm_medium=cpc&utm_campaign=380212636&utm_content=1241348818236351&utm_term=highpointscientific&msclkid=ef3beb05fcfd1c6d63fa8f70d68135fc https://www.telescope.com/SkyLine-10-Dobsonian-Reflector-Telescope/p/113095.uts

Mike, I miss-wrote the Orion model name; it is indeed the GSO made SkyLine version I’m considering, and I’ve corrected my earlier post. The only obvious downside of the SkyLine compared to the SkyQuest is its increased weight. Beyond that, and for a very small additional cost, the Skyline has the advantages you’ve noted plus what I hope are better motion bearings. My only remaining question, which I haven’t found the answer to, is wether one mirror is better figured than the other. Louis, I’ve carefully considered the Explore FirstLight series scopes and concluded that while the trunnion altitude bearings are likely smoother than the alternatives their greater exposure makes them more susceptible to the kind of damage I’m likely to inflict in transport.

True enough, but there was also a beautifully hand made 10” Dob with a f/3.3 hand figured primary and secondary I hadn’t mentioned. It was perfectly sharp in very small zones that seemed to move with your eye, but overall I thought it was a bit soft. Perhaps it hadn’t fully acclimated when I looked through it? We’ve pretty much settled on a 10” Dob for Monica, and of the readily available scopes State side the 10” Orion SkyLine seems the best choice. I’ll likely wrap up my research in the next couple of days and place my order later in the week.

The soap trick worked beautifully, Monica is once again in love with Dobs, and I can see a new 10” Dob in our future. I never did get to star test collimate the primary mirror, but the Barlowed-laser collimation I did on my work bench was good enough that the moon showed astounding detail, and M13 took on a decidedly 3D appearance with dozens of resolved stars in the foreground surrounding and framing the luminescent core. There were a couple of other large reflectors at the party, including a 14” Meade Schmidt-Cassegrain, but the big Orion out performed them handily, being brighter, having more contrast, and being sharper both on and off center. Honestly, I was surprised by how much better it performed than it’s far more expensive peers, but perhaps their mirrors were dimmed by age, and their collimation wasn’t optimal. I don’t know, but I was very impressed with the Orion 12” Dob.

It would seem that Moshen’s test of a SVX127D shows StellarVue already makes scopes that are as good or better than TEC and AP. Unless I’ve misunderstood Maciek’s post from that test thread, correction for spherical aberration in red, green, and blue was 0.994, 0.994, and 0.968, respectively. I can’t recall any scope from AP or TEC or anyone else that’s tested that highly, and that those numbers came from a 127mm doublet is astonishing. Almost as astonishing is that that sensibly perfect SVX127D cost it’s owner $3,000, while the AP 130GTX will cost it’s owner $8,000. It would be a very good 130GTX indeed, if it could match the SVX127D’s performance.

Michael and Louis, thank you very much for the tips. Louis, thank you for the link to the fiberglass reinforced wall panel; I’ve heard very positive comments about its efficacy as a Dob bearing surface. Michael, where might one source that large diameter bearing you’re using?

There are a lot of mirror cleaning videos and some of them are real horror shows. I cleaned the mirror using the technique presented in the Optical Wave Lab video. It seemed to me their technique presented the least risk to sleeking or scratching the mirror without resorting to polymer film.

Last fall my wife, Monica, and I volunteered to bring a couple of telescopes to a star party organized by our local Land Trust. My wife had never operated a telescope other than to focus one of our small refractors on a target I had located, so thinking it would be easiest to start small and wide I put her in charge of our 50mm achromat mounted on a photo tripod, while I watched over our 102mm refractor. Fifteen minutes into observing and without a word Monica abandoned her post, disappeared, and left me to run both scopes on my own. I never even saw her leave. It wasn’t until the end of the party two hours later that I found Monica working an old 12” Orion Dob owned by the Land Trust, but without anyone at the Trust who knew how to run it. Adjustment knobs were missing, the finder was hopelessly out of alignment, and the filthy 10mm Plössl eyepiece mounted in the focuser made for a dim and tiny field of view, but Monica somehow worked through it all and was happily showing Jupiter and Saturn to the party guests. A little over a month ago we again volunteered to help at the next Land Trust star party and I thought it might be worthwhile to go through the dilapidated Dob and bring it up to snuff so Monica could run it again. We borrowed a larger vehicle, retrieved and brought the Dob home, and I went to work. Here are the two scopes compared. I suppose I can see the attraction…maybe… The Dob mirror was reasonably clean considering it resided at a dusty ranch, but since I hadn’t ever worked on a Dob I decided to try my hand at cleaning the mirrors. Here’s the before photo showing the not so great secondary mirror alignment and some curious markings on the primary mirror: I used a few tomato cans to lift the mirror from the cell… and took a closer look at the mirror which showed some curious marks, some of which were scratches: Perhaps this little fellow I found wandering within the tube had something to do with the marks: It appears the Dob was jostled a bit as well, as shown by the witness marks showing the mirror rotated a bit on it’s cell: And here’s part of the mirror after cleaning. Shame about the scratches, but I’m pretty sure they won’t effect viewing: Long story short: the mirrors cleaned up nicely, I centered the secondary holder and focuser, reset the main mirror cell, collimated the secondary mirror and Barlow laser collimated the primary mirror, assembled the various remaining bits and bobs, and all just in time for several weeks of strong gale winds. To pass the time while waiting for a break in the weather to star test the scope, Monica and I were watching Ed Ting’s video comparing various Dobs and completely out of the blue Monica declared, “I’m in love with Dobs!”…. “WHAT DID YOU JUST SAY!?!”………“I’M IN LOVE WITH DOBS!” I’m a committed refractor fan, perhaps an overcommitted fan, and it’s possible I may have overreacted a bit, but I shot her a glance that possibly looked a little like this: I eventually regained my composure and dismissed Monica’s declaration of love as simple infatuation, but I freely admit I was a bit taken aback and perhaps a little hurt. A couple of days ago we had a brief pause in the storm and we wrestled the Dob through the kitchen and into the back yard. The seeing was atrocious and so I wasn’t able to evaluate collimation or optic quality, but we were able to wrestle the big Dob in the general direction of M13. When I say wrestle I’m not kidding. It took tapping, shoving, rapping and banging to move the Dob onto M13, and more tapping, shoving, rapping and banging to keep it there. The Teflon azimuth bearings were by no means up to the task, the stiction was horrendous, and Monica and I were both frustrated and disappointed by how poorly the mount performed. I asked Monica whether she was still in love with the Dob and she sadly confessed that much of the shine was lost. I felt bad for Monica, and I want her to have a great experience at the star party, but nothing I did after our short observing session seemed to help make the mount livable. That is until I remembered a trick one of the regulars at CloudyNights mentioned: Ivory Soap. I removed the scope tube, flipped over the mount, and rubbed the Ivory bar soap liberally over the bearing surface. Initial indications are that the soap’s made a huge difference in reducing stiction, but the final test will be Friday night at the star party. Fingers are crossed for favorable weather and a successful night with the Dob. We’ll see.

Greetings Maciek, Interesting discussion and thank you for sharing your experience and knowledge. Concerning orientation, you’re undoubtedly correct in that orientation will have no effect on what we see at the eyepiece. I’m less convinced that a sensitive test, such as laser interferometry, won’t respond to inclination. Our eye is a poor arbitrator of small errors in optical instruments, in most cases we’re unable to distinguish between 0.80 Strehl and 0.99 Strehl optics, and we probably shouldn’t rely on what our eye can or cannot detect as a basis for evaluating small differences if small differences are what we’re interested in. That our eye cannot detect the effect of orientation doesn’t mean that there is no effect or that it is undetectable. The question is whether a Zygo interferometer can detect the effect and whether that might result in a reported difference, say between 0.98 and 0.96 Strehl or greater. I don’t know the answer, but given the sensitivity of laser interferometry I’d be surprised if an optical element tested vertically and horizontally would yield the exact same Strehl number. I’ve wandered into the weeds a bit to remind myself that while testing is an undoubtably important part of evaluating anything, testing without an understanding of its inherent weaknesses can be misleading, and that precision and accuracy are two entirely different things. If a manufacturer claims their instrument has a minimum manufactured Strehl of 0.98 and a careful independent tester finds it to have a value closer to 0.80, then Houston, we have a problem! If that same tester reports 0.94, one might reasonably wonder if the difference could be attributed to external variables related to differences in methodology.

Hi Maciek, I’m by no measure an optical expert, but given that StellarVue uses their Zygo interferometer primarily as a tool to produce consistently repeatable results while figuring a multitude of optical elements, I’d expect that them meeting their internal standards would be the the norm, rather than the exception. So why the difference between the two scopes you’ve mentioned? We can expect small differences between scopes due to manufacturing tolerances, but significant differences may have other causes. I place a high value on testing, but variability in testing methodology can have a profound impact on the results, and especially so when testing for minusculey small differences. I’ve tested a variety of materials under ASTM (American Society for Testing and Materials) standards and by far the most important part of reliable testing is controlling variables. There are no sensitive tests insensitive to external variables and it’s the job of the tester to understand those variables and to minimize them to the degree possible. Here’s two examples of obvious variables: StellarVue tests their optical elements oriented vertically to more closely mimic how we normally use our scopes. Most other testers orient their test subjects horizontally, because it’s usually more convenient. Next, after they’ve been worked, StellarVue let’s their optical elements reach ambient temperature overnight in a carefully temperature controlled room before testing. How were the two scopes mentioned tested by their respective testers? We don’t know, but unless their methodologies were identical, and identical to StellarVue’s, I would not expect three identical results. I recall a photograph of one optical test showing a large computer beneath the test bench. It’s probable the heat rising from the computer didn’t do the test results any favors, and that same scope tested in a cool basement or garage might appear to be a different instrument entirely. We think of optical glass as dimensionally stable, but anyone who’s watched the view through their large reflector change in realtime as the mirror cooled could be convinced otherwise. Even with my own modest refractors I can easily discern the optical difference between a scope I just took outside and that same scope after its cooled for half an hour. Most of us viewing in average seeing can’t tell the difference between a diffraction limited scope and a sensibly perfect one if the image is in focus. Perhaps the significantly smaller test result differences between some scopes can be at least partially attributed to variables related to methodology?

Maciek and 900SL, I believe you are both correct in that the optical tests are reliable and valuable, and that there is an overtly anti-SV cohort which aggressively seeks to poison every discussion involving StellarVue. As to the former, testing improves the breed for all of us and should be encouraged. Many telescopes of various makers have undergone testing, some revealing themselves to be better than expected and others, including some of the most revered makes, coming up short. Not all Televue, Astro Physics, and APM scopes test well either, and the test results are there for anyone who’s interested. What’s important are the actions the maker takes to protect their customers and to improve the quality of their scopes. Concerning the anti-SV group, it’s difficult to understand the motivations of a group that seeks to harm one of the very few telescope makers left in the free world and that makes available excellent telescopes in the quantities that have a tangible positive impact on amateur astronomy. It’s a tough nut to crack. After some thought the only reason that makes sense for me is that they harbor a misguided fear that ascension of StellarVue as a premier telescope maker threatens the status of their own favored brand. Status worship and insecurity is at the root of many social ills, some trivial and some very dangerous, and while I’m surprised to see it applied to telescopes I probably shouldn’t be. I’m grateful for all of my StellarVue, Astro Physics, and TeleVue gear, and I see no need for or value in elevating one brand over another.

Those three screws you put into the secondary mirror holder - I think you’ll need to remove them. I believe those screws you installed are now covering the metric grub screws which you will need to adjust with the help of a properly sized Allen wrench, like so: The actual collimation is a bit more involved than is easily put to writing, but these gentlemen do a very good job of explaining and demonstrating the principles: You’ll notice they’re using a laser collimator, which needn’t be expensive. Anyway, this is a good approach to get you on the right path. Good luck!

That leaves room for at least five more telescopes: one each for globular clusters, open clusters, double stars, nebula, and finally one for grab-and-go. You’ve already compromised by combining the planets and moon, which are clearly completely distinct celestial objects, and so you’re entitled to at least a couple of more scopes!

Great question, Gerry, and I’m afraid I don’t know. My shortest eyepiece is a 3.5mm Nagler which provides a magnification of 204X with an exit pupil of 0.5mm. The scope is capable of much much more, but I’m not and so I haven’t explored its limits. A smaller than 0.5mm exit pupil means I’m learning more about the junk floating around within my eyeballs than the surface of the moon, but you’ve now got me curious and the next time the notoriously abysmal seeing in my area improves beyond the typical Pickering 3 or 4 to at least 5 or 6, I’ll throw on a Barlow and see what happens. I can say that the SVX102D resolves stars in M13 and shows detail in the disk of Andromeda even in mediocre seeing, but that’s probably not unusual for a 4” scope. I can also say that I don’t see any reportable distinction between the views through my StellarVue doublet or my Astro Physics 92 Stowaway triplet; they’re both excellent scopes and easily better than my skies, eyes, or skill as an observer. My apologies, Gerry, I wish I could be more helpful.

Gerry, I’ve got the SVX102D, the smaller brother of the SVX127D. The optics, fit and finish, and mechanics are all extraordinary. It is in every way the equal of my Taks and my Astro Physics 92 Stowaway, and is in some ways their superior. I would expect no less from the SVX127D, and with 55% more light gathering objective area views through it should be brilliant. StellarVue doesn’t sell through dealers, and when you purchase one of their scopes you will be working with one of their people. No middleman , no dealer markup, always a StellarVue employee. Whomever you work with at StellarVue, and it can easily be the owner, Vic Maris, customer service is exemplary. If you can swing it, order your SVX127D with the Feather Touch focuser. It’s a bit more, but the focuser is a work of art and should you ever need it serviced the people at Starlight Instruments will take excellent care of you. All in all, I can see nothing but years and years joy coming from owning this instrument. It’s not inexpensive, but one look through it and I doubt you’ll think of the cost again unless it’s to reflect on what a terrific bargain it is. That’s how I feel about my own StellarVue scope. Good luck!

You’ll hear frequently that many scopes are under mounted and you’ve just had your first practical lesson on exactly what this means. Given the size and weight of the 150PL, and the strength of the mount and tripod, this setup will be sensitive to touch and prone to vibrate more than is desirable. Some of that you can work around with practice and experience, but external forces like wind and ground vibrations are something entirely different and something you’ll occasionally have to live with. The solution is a stronger mount and tripod, but that something you can explore when you’re ready. In the meantime, practice using a light touch with the focuser and avoid unnecessary contact with the eyepiece. It’s all part of learning how to get the most from the equipment you have.

This should help you to locate yourself…

A pox on floaters!

I’ve located the source: https://earthsky.org/astronomy-essentials/venus-after-sunset-greatest-elongation/ It appeared in EarthSky’s Astro-Essentials section.

This is an extraordinarily concise and elegant graphic. Is this something you put together yourself, or is available from a website and if so which? It would be great to have similar graphics for all of the planets.

Here’s a 50 mm f/5 scope you’re less likely to see outside of the U.S. It’s made by Long Perng in Taiwan for use as a finder scope, and was imported by Astronomics and sold through their website. It didn’t sell well because the optical tube diameter was too large to fit inside most finder rings, and to move them Astronomics reduced the price to $45. A well known member at CN purchased a couple to fill out an order and found them to be incredibly sharp. He posted his findings, others likewise found them to be terrific little scopes, it became a minor cult classic amongst its owners, and it eventually sold out and is sadly unlikely to return. Here’s a closer look as it as it sits on a Manfrotto 128 fluid head and Manfrotto 190 tripod; peep sites are an add on from the hardware store. With the exception of the plastic thread-in lens cell and thread on lens cover, the entire scope is made from steel, glass, and thick wall aluminum tube. The diagonal is a correct image prism and above it sits a helical focuser. The coated lenses are a cemented doublet. I use mine for pretty much everything from wildlife and bird watching to splitting doubles. At least one owner has split Porrima (γ Virginis, ~3.3”), and I was able to split Castor (5.2”) at 36x magnification, which is probably more difficult than splitting Castor at double the magnification. A 32 mm Plössl or 24 mm Panoptic will give a magnificent 6.2° field of view for sweeping through Scorpius and Sagittarius. I hear it makes a pretty good finder as well. It’s a bit like a Mini-Borg for 1/10th the price.

Here’s a parafocal ring in action for those of us who might not have seen one in the wild. The parafocal ring reduced the inserted eyepiece barrel length from a prism smashing 36.7 mm, to the quite safe 29 mm shown. You can get a set of three rings from FLO here: https://www.firstlightoptics.com/adapters/astro-essentials-parfocal-rings.html

Those are two of the many attributes of a small refractor that make them so appealing. On many of my refractors I don’t even use a finder, I simply aim them by sighting down the long tube from where I’m positioned at the back end of the scope.