Jim L

Thank you very much, Ryachu; I’ll try lubricant.

Very nice work! The batteries in my same red dot finders seemingly last forever, so I don’t have that problem, but it would be nice if the top rotating brightness switch were easier to turn so that doing so doesn’t compromise the alignment of my scopes. Now that you’ve had one apart do you have any thoughts on how the rotating switch can be modified for easier rotation?

I’ve lived in the northeast, southeast, northwest, southwest, and center of the USA for the past 67 years, so let’s just leave it at we’ll agree to amicably disagree. As to the question of country of manufacture, which seems of little importance on the CloudyNights website, but appears to be the object of intense interest here, I offer the following possible explanations: 1. The general consensus in the States is that China - and we are talking about China here though limited to its relationship to amateur astronomy - can manufacture pretty much anything you want to any level of quality you desire so long as you’re willing to pay for the effort required. 2. Most of us understand that making the very best of anything doesn’t presently play to the strength of Chinese manufacturing. For example, we can all compile a list of extraordinarily good Chinese eyepieces and telescopes, none of which are generally regarded as the very best available. Those honors go to Takahashi, Masuyama, TeleVue, Astro Physics, etc. The strength of Chinese manufacturing is to make goods that are almost as good as the very best but at a fraction of the cost of the very best, and to sell them in large quantities. It can be characterized as a high-quality moderate-cost high-volume approach, and it is an excellent model. I am reasonably certain that TeleVue can have eyepieces manufactured in China to the same quality as those currently made in Japan and Taiwan, but there are several impediments. The first impediment is cost, because the quality of Chinese eyepieces won’t match the existing TeleVue lines without additional design, manufacturing, and material resources; all of which add cost. There’s no free lunch. The next impediment is perception base on understanding of the present Chinese business model and acceptance or rejection on the part of the consumer as to whether they believe China will to be able to pivot from their existing highly successful high-quality moderate-cost high-volume model to the apex-quality apex-cost low volume model with a questionable outcome. I don’t see what’s in it for China, perceptions take time to change, and time is money. I doubt China will be interested. 3. There is a general feeling that buying locally to support your friends, neighbors, fellow countrymen, kindred spirits, etc., is a good thing, and undoubtedly universal throughout the world. There does not have to be a nefarious element to this feeling. Of the 185 posts in eight pages in CloudyNights about the TeleVue survey there is only a single post that mentions China, and that one does so favorably. Given that the question of undercuts is brought up 84 times I think it’s clear what the folks over there consider to be the important issues raised by the survey.

I can’t speak to the guitar world and I would not take the reviewer you’ve referenced at all seriously, but my experience contradicts the notion that Americans “are often very convinced that anything made in the USA is automatically superior.” In fact, I don’t think I’ve encountered that particular bias for as long as I can remember, so sometime in the 70’s or there about. It’s not really a thing here. In fact, as far as Televue eyepieces are concerned pretty much anyone who owns or is contemplating purchasing any knows that they’re made in either Taiwan or Japan, and that none are made in the USA. Manufacture in those countries doesn’t seem to hurt either their popularity or reputation here in the States one bit.

And eyepiece barrel undercuts!

Be careful Peter; some filters and Barlows may have a smaller outer diameter than a standard 1.25” eyepiece barrel and sneak by the exclusionary collar.

Continuing the astronomy gear theme of never standardizing anything, neither eyepiece nose length, Barlow nose length, filter length, nor diagonal depth can be counted upon to protect your diagonal’s mirror or prism from damage if your eyepiece or filter hits the diagonal reflective surface when inserted. Further, while some diagonals protect themselves with an internal excursion lip many, or even most, do not. A look at one of my Takahashi diagonals next to a Nagler zoom, followed with a couple of quick measurements with a plastic caliper, made me realize there’s a problem, and further investigation showed it wasn’t limited to the aforementioned items and was actually quite common. Fortunately, diagonal strikes are easily prevented with a few simple calculations and readily available Astro accessories. I took a systematic approach by first recording whether each of my diagonals had a functional protective lip and, if not, the distance from the top of the eyepiece holder to the diagonal mirror or prism. I next recorded all of my eyepiece and Barlow barrel lengths to determine which ones would contact the diagonal reflective surfaces. If you install filters at the ends of your eyepieces or Barlows you’ll want to measure them and include them in your calculations as well. A simple spreadsheet later and I had a quick and accurate means of identifying eyepieces that weren’t a problem under any circumstances (blue font), those that were a problem with filters installed (magenta), and those that were always a problem in unprotected diagonals (red). If your numbers don’t quite match with mine, it’s probably that I added a “safety factor” to most of my measurements to err on the safe side. The worst offenders were made safe with parafocal rings, readily available from FLO in the UK and Europe, and Agena Astro and even Amazon here in the States. To make the grub screws that secure the parafocal rings on your precious eyepieces and Barlows less bitey you can remove the sharp tip surface with a sharpening stone and a drop of oil. Doing so makes a tremendous difference and I blunt all of my grub screws on all of my telescope gear. By checking combinations of eyepieces, Barlows, filters and diagonals it’s simple enough to prevent strikes on your diagonals by taking precautions before your observing sessions. For example, if I’m using eyepieces that can strike a diagonal with a filter installed, I install the filter on the diagonal instead of the eyepiece. Takahashi diagonals are a special case since their nosepieces do not appear to be threaded to accept filters, but other remedies are possible. Good luck and happy observing.

You can point your scope at any star, planet, or any other celestial object listed within the Az GTi SynScan Pro menu, choose that object from the menu, press the “Point and Track” button on that object’s info page, and it will track that object. While using the point and track function here’s no need to align the mount, nor any benefit to do so, though I suspect tracking will be better if the mount is level. This is how I usually use my Az GTi mount as I find the point and track seems to work far better than it’s goto function.

The FC100DC is an excellent match for the Sightron alt-az mount, though in my case on a Gitzo GT5533LS tripod. A More Blue dovetail clamp and a couple of spare slow motion cables make using the mount easier. I can’t quite reach zenith with the way I’ve got the mount set up now, but it’s close enough for my purposes and if I need to reach higher a quick adjustment of the azimuth arm will get me there. The goal was a portable and lightweight grab-and-go setup I could race sucker holes with and that fit comfortably within my quite small ‘91 Miata. The Tak DF and DZ alternatives to the FC100DC were very tempting, but being significantly heavier they wouldn’t have integrated nearly as seamlessly with the Sightron/Gitzo tripod and mount. I don’t expect to see a difference through the eyepiece between the DZ and my DC Tak very often, if ever, but the weight difference between them would be noticed every time the scope is used. It’s hard to make a wrong choice with a 4” Tak, but depending on your needs there can be better and less better choices.

To build upon John’s excellent advice, I use a small penlight held up to the side of the Cheshire eyepiece. It’s also helpful to remove the crosshairs at the end of the Cheshire as they’re nothing more than a distraction when collimating a refractor. Sometimes they unscrew, sometimes you’ve got to cut them. Next, you’ll need more hands than you’ve got to hold the scope, hold the penlight, rotate the Cheshire, and adjust the focuser or lens cell alignment, so mounting the scope in a stand or low tripod makes life easier. If you aim the scope at a dark matt surface the reflected circles within the Cheshire eyepiece will be easier to see clearly. Bonus points if you buy yourself a close focus monocular to make collimating even more precise but you tell your wife you bought it for her to look at hummingbirds in the garden and she has no idea it’s really a tool for your telescopes. This SvBony monocular won’t focus close enough for the short focal length ST80, but it works for most of my other refractors. My wife’s never seen this configuration, and I plan on keeping it that way. All set to go with #8 and #12 Wratten filters in the tripod basket.

The rings look nice and concentric, Stu, though if I squint hard enough I believe I can detect just a touch of what the experts call chromatic aberration.

For future reference, here’s another source for the Tak style universal finder bracket: https://www.amazon.co.uk/Ninyoon-Universal-Aluminium-Telescope-Finderscope/dp/B09TKYY7LY/ref=sr_1_41?crid=3RUNBABAM9NU3&keywords=Telescope+Finder+bracket&qid=1700169554&sprefix=telescope+finder+bracket%2Caps%2C272&sr=8-41 Here’s the one I use, and which I prefer because it’s secured through holes rather than slots: https://www.aliexpress.us/item/3256804477322418.html?gatewayAdapt=glo2usa Here’s the slotted version for under $10 if you aren’t in a hurry: https://www.aliexpress.us/item/2255800598317172.html?spm=a2g0o.detail.0.0.6b281cafcEQtoU&gps-id=pcDetailTopMoreOtherSeller&scm=1007.40050.362094.0&scm_id=1007.40050.362094.0&scm-url=1007.40050.362094.0&pvid=b81b895b-2733-47d6-b614-c2c5a16d7d56&_t=gps-id:pcDetailTopMoreOtherSeller,scm-url:1007.40050.362094.0,pvid:b81b895b-2733-47d6-b614-c2c5a16d7d56,tpp_buckets:668%232846%238112%231997&pdp_npi=4%40dis!USD!14.01!8.97!!!14.01!!%402103247117001700664644481e9142!10000007813430415!rec!US!2861702980!

The screws that hold the lens cell to the tube, like the screws that hold the focuser to the tube, all allow for a small amount of movement. That freedom of movement of the lens cell and the focuser can, on the one hand, cause mis-collimation, and on the other hand, help you to collimate the scope if it is out. I loosen one set or the other enough that I can move the lens cell or focuser, but against some resistance, all while checking collimation. When it’s right I tighten the screws while doing my best to maintain correct collimation. As to wiggling the crown and flint objective, that’s a hit or miss proposition because the two elements are held relatively loosely within the cell. You can tighten up the fit of the elements within the cell using small pieces of thin adhesive tape at several spots along the plastic cell annulus. Doing so improved the objective alignment for my own ST80. Good luck!

I ordered a Sightron mount from Astro Hutech here in the states and my impressions align very closely with yours with a couple of additional observations: The “null” you’ve noted in your mount was quite large in the alt axis of my unit, amounting to somewhere over 30 degrees. Next, the single screw saddle may have a propensity to loose some grip after tightening. On two separate occasions I rechecked the saddle screw grip and found it alarmingly loose. I don’t know whether it’s change-in-temperature related or from some other cause, but it won’t hurt to recheck the saddle screw occasionally over an observing session. Better yet, replace it with a more secure dovetail saddle from ADM or More Blue. Lastly, the silver finish doesn’t seem to be particularly tough and my mount arrived with a couple of small rub marks partially through the finish from shipping, which bodes poorly for long term durability of at least the silver color choice. So, while there are more than enough very good features to make the Sightron a worthwhile light weight mount, a bit more care on the part of the manufacturer to eliminate some niggling issues with materials and assembly could make this an excellent choice.

Comparing the measured/evaluated aberration spots of the SvBony SV135 7-21 mm zoom and the Baader MkIV 8-24 mm zoom a bit more closely: The third, fourth, and fifth numeric columns contain the aberration spot sizes of the center, zone, and edge of of eyepiece view in angular minutes through f/4 optics. Smaller spots are better, but Ernest notes that if the aberration spots are less than 10 angular minutes the quality of the image can be evaluated as perfect. Source: https://astro--talks-ru.translate.goog/forum/viewtopic.php?f=32&t=1483&sid=cd0a88f216e605da4c3644bea4fb42f5&_x_tr_sl=ru&_x_tr_tl=en&_x_tr_hl=en-US&_x_tr_pto=wapp&_x_tr_sch=htt Edit: I should probably add that aberration spot size is only one of many criteria that should be considered when evaluating eyepieces, and that compromises made by the designer in one area may yield benefits in another, so that as interesting as the comparison between the two zoom eyepieces may be it’s certainly not everything.

Hi Joe, The skies overhead aren’t particularly dark being that we’re staying at the SpaceX Starbase, which is a beehive of activity both day and night. I’d say it’s not as light polluted here as it would be from within a small to medium sized city, but it’s certainly not a dark site by astronomy standards from my son’s back yard. The band of the Milky Way isn’t at all visible. What I think the site has going for it, and which probably helped Monica spot Enceladus, is that Saturn was in the southeast over the warm, moist, and relatively steady air over the gulf. High altitude frozen water vapor that scatters light at so many other locations seemed completely absent, and glare from Saturns disk and rings was far less intrusive than is the norm from my own home northeast of San Francisco. While Monica saw Enceladus using averted vision I could not, so good eyes also play a role when objects are at the margin of what’s possible to see. Then there’s the issue of having sufficient aperture, and the 6” SCT was probably close to its practical limit as well for a visual magnitude 12.4 object. Monica and I were actually chasing Saturn’s Cassini Division when she saw Enceladus. Since I didn’t see either I guess I’ve now got two targets to look for over the next few weeks.

My wife, Monica, observed Enceladus last night using a Celestron 6SE SCT and looking through a SvBony 7-21 mm zoom eyepiece. We were observing from the Gulf of a Mexico coastline just north of the Mexican border. Seeing and transparency were listed as average in Astrospheric. This was the alignment at the time:

Hi David, I’m glad you caught a glimpse of the Cassini Division. In my case it’s the atmosphere, not the scopes, that are probably the limiting factor, though next year, and for the next couple of years after that, I’m pretty sure it will be beyond my skills and equipment to see the division, however favorable the atmosphere might be. But still, it was a great night. The two things I’m most pleased about last night’s observing were how beautiful Saturn is if seeing is at least average, and just how well my son’s relatively compact 6” SCT performed. About that 6SE SCT, I don’t think it gave away much to my better refractors, or at least under the conditions last night it didn’t.

I’ve been chasing Saturn’s Cassini Division from my home northeast of San Francisco since early August; unfortunately unsuccessfully. I’d seen it quite easily multiple times over the past couple of years through a variety of small refractors in the 72 mm through 102 mm aperture range, but recent poor seeing and Saturn’s increasingly unfavorable tilt have conspired to hide the Cassini Division from me these past several months. I’m optimistic things are about to change. My wife, Monica, and I are visiting our son’s family in Boca Chica, Texas, which is located on the Gulf of Mexico where Texas and Mexico meet along the Rio Grande river. It’s flat, humid, and this time of year breezes are light, so I’m hopeful seeing will approach the fabled excellent levels south coastal Florida is famous for. Conditions last night weren’t optimal, and Astrospheric showed average for both seeing and transparency, but this was only the first night of many to come. We’re using my son’s Celestron Nexstar 6SE Schmidt-Cassegrain (150 mm aperture, 1500 mm focal length) telescope. We purchased it as a gift for my son in 2020, just before the Jupiter-Saturn Great Conjunction, but I’ve never looked through it and until last night I had no idea whether it was good, bad, or indifferent. Having read mixed reviews of Schmidt-Cassegrain scopes and reports that some of them can be, “soft”, I was I bit concerned that my son’s scope might be a dud. It is not a dud, and in fact quite the opposite. My first view through it was using the Celestron 25 mm Plössl (60X) and 90° prism star diagonal (94115-A) that came with the scope. The large, unfamiliar to this refractor guy central obstruction black hole shrunk and then disappeared completely as I turned the focus knob, revealing a beautifully sharp planet and rings, multiple pinpoint moons, and a stark black background. We were off to a very promising start indeed. Next up was the only other eyepiece my son owns: the very capable SvBony SV135 7-21 mm zoom. The change in focal length from the 25 mm Plössl to the 21 mm zoom setting was a welcome change from 60X to 71X, and concentrating a bit more on the finer details I could easily see four moons using direct vision. Skipping the intermediate range between 21 mm and 7 mm I went directly to the 7 mm zoom setting with it’s 214X magnification. While the view remained impressively coherent, atmospheric ripples sweeping across the disk and rings showed that I was beyond what the seeing could comfortably support and so I backed down to the 15 mm to 10 mm zoom range at 100X to 150X magnification, respectively, and this is where we remained for the rest of the evening’s observing. At lower magnification Saturn showed a pale yellow-orange pastel disk with some vertical differentiation provided by indistinct horizontal zones, and bright, crisp, rings separated from the planetary disk by black space. In the greater 100X to 150X magnification range the planetary disk zones could be further differentiated into multiple pale bands with averted vision, and the rings showed a more marked distinction between the dimmer outer “A” ring and the brighter inner “B” ring, but try as we might neither Monica nor I could pull the Cassini Division from the rings. Sometimes I thought, “almost, it’s right on the edge, I’ll glimpse it if seeing will sharpen for just a moment”, but it never happened. What we did see were five of Saturn’s moons, in my case, and six, in Monica’s. And while the attached image was taken from SkySafari 7, it’s very much like the view at 100X magnification through the 6SE last evening. Putting labels to moons, below, of the six moons shown only visual magnitude 12.4 Enceladus eluded me, though Monica was able to pick Enceladus out using averted vision. We’ll be here on the Gulf Coast for another couple of weeks, so I’m hopeful we’ll have some nights with better than the “average” seeing Astrospheric reported last night. If so, and if the Cassini Division reveals itself, I’ll let y’all know. Cheers!

Undercuts are roughly as universally popular as paper cuts.

The difference between Ernest’s reviews and most everyone else’s is the difference between objective and subjective analysis. Ernest bench tests eyepiece optics; to my knowledge that makes his analyses quite rare in the amateur astronomy community, if not unique. Quantitative analyses takes no prisoners, makes no allowances for the name on the eyepiece or its price, and feelings be damned. It doesn’t replace the expert subjective analysis of extraordinarily experienced and astute reviewers such as our own Don Pensack and Bill Paolini, but it is an extraordinarily powerful approach and one well worth paying close attention to.

I believe there’s good reason to believe that the Baader is not “better”. If I’m interpreting Ernest Maratovich’s evaluations of the SvBony 7-21mm , SvBony 9-27mm, and the Baader MkIV 8-24mm zooms correctly, it appears Ernest found the SvBony zooms optically superior to the Baader, and decidedly so in the case of the 7-21mm zoom. 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 https://astro--talks-ru.translate.goog/forum/viewtopic.php?f=32&t=2695&p=77035&hilit=Baader&_x_tr_sch=http&_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=wapp#p77035 Having read Ernest’s reviews I came to the same conclusion you did, and passed on the $340 Baader zoom in favor of the $32 7-21mm SvBony zoom. In fact I’ve done that at least five times so far.

That Dob is too large to fit comfortably onto the Mighty Blue 50 🙂

50 mm vs 300 mm

I have several of those eyepieces (SV135), and they’re excellent. Here are two very good reviews of the eyepiece from Ernest’s website, Astro Talks, https://astro--talks-ru.translate.goog/forum/viewtopic.php?t=4542&_x_tr_sl=ru&_x_tr_tl=en&_x_tr_hl=en-US&_x_tr_pto=wapp&_x_tr_sch=http 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 They’re my most often used eyepiece; light, versatile, decent eye relief, and sharp.