Louis D

I found I was getting the most detail on the planets this year using my binoviewers with a pair of microscope eyepieces and a Meade 140 Barlow nose piece. The planets were so bright that I couldn't really see good details without having to filter them down. This was completely unnecessary with two eyes viewing at once. That, and my brain was able to pick out finer details using two eyes, especially if I bumped my scope and allowed my brain's motion detection circuitry to kick in while it settled.

You might also want to check collimation on that Newtonian with a cheshire. This is assuming it has the ability to be collimated. I'd start with some Revelation/GSO Plossls or similar. Perhaps 32mm and 12mm to start with. Eye relief will be a bit tight on the 12mm. If the view still looks terrible, it's the scope or seeing conditions and not the eyepieces.

Yes, but you weren't very specific about "a poor fpl53 design before it was outperformed by a fpl51 scope". Had you said "a poor fpl53 doublet/triplet before it was outperformed by a fpl51 doublet/triplet", then I wouldn't have made my point. I brought it up because of the expense of FPL-53 has caused a lot of ED/APO designs to use FPL-51 triplets instead of FPL-53 doublets. So, in that sense, it is a like for like comparison price-wise.

Some of the FPL-51 triplets rival FPL-53 doublets.

Tracking is possible with Dobsonians with either a goto drive or an equatorial platform. Both options are outside of your budget, and neither is ideal for imaging.

I wouldn't read too much into the absolute brightness of each eyepiece taken in isolation. The camera was on auto exposure for each eyepiece, and the brightness of the room may have also changed as more or less light streamed in the nearby windows as the day wore on during testing. What's more relevant is light falloff center to edge within each exposure for each eyepiece. Notice how the RKE gets dim near the edge? Notice how the Aspheric fuzzes out near the edge? These are the relevant sorts of things to look for within each eyepiece's image. The Meade HD-60s are purported to have 6 elements each. Four in the upper, positive section, much like a 1-2-1 Konig and two in the lower, negative section, much like a Barlow or Smyth lens. So, most likely 6 elements in 4 groups. I can't find any definitive diagrams for you, though. The 24mm APM UFF has 8 elements in 5 groups as seen below: The Panoptic uses 6 elements in 4 groups as seen below: The Aspheric is three elements as seen below:

The Hyperion would yield a significantly wider apparent and true FOV relative to the Meade Plossl. It might even perform fairly well in your f/10 scope. Unlike the rest of the Hyperion line, though, it does not perform very well in faster scopes below f/8 or so because it is basically an Erfle variation. I would get a 24mm APM Ultra Flat Field or one of the other rebrandings (Altair, Meade, Celestron, Orion) out there instead. It is well corrected even in faster scopes should you ever decide to buy one. Zooms are very narrow at the long end of their range. Most affordable zooms tend to have a 35 to 45 degree apparent FOV, so actually less than an equivalent Plossl at that focal length. They do get decently wide (50 to 70 degrees) at the short end of their range. The Vixen SLVs are very sharp, well corrected, consistent long eye relief, and have excellent stray light control. They tend to perform more like premium wide field eyepieces, minus the wide field. I would only recommend that at 12mm and below because there are better options at longer focal lengths.

Eyepiece tip-tilt is still a concern with the OVL style collets because they're not that deep. I have the Arcturus version, and eyepieces without undercuts work much better than those with them. I have to jam eyepieces with undercuts into the holders while tightening them to prevent them from tilting. At first, I thought my binoviewers were out of collimation until I realized I could rotate the diopter adjuster and bring them back into closer collimation. I then noticed that the eyepieces weren't seated all the way into their holders.

Wide field eyepieces tend to be addictive. You may find yourself wanting to go wider and wider until your wallet is empty. Think of looking through a paper towel tube versus a toilet paper tube versus a one inch long section of the latter. The field magnification remains the same, but the field of view increases at each step. You're confused by the two usages of field of view (FOV). One is true FOV (TFOV) and the other is apparent FOV (AFOV). TFOV is how much of the actual sky is visible and AFOV is how big of an angle does it subtend across your eye's field of vision as I was alluding to above with the various tubes. As an extreme example, the original ten or so 9mm ES120 eyepieces came without field stops and had a TFOV just about the same as a 32mm Plossl. This is because both had about a 27mm field stop (or effective field stop) which is what determines how much of the telescope's image circle (camera speak) is magnified by the eyepiece. The AFOV though went from 140 degrees (ES-120) down to about 50 degrees (Plossl). Magnification also more than tripled. Thus, the experiential difference between the two is enormous.

True, but due to distortion, it has a 66° effective AFOV. At 27.5mm, it has just about the largest possible effective field stop in a 1.25" eyepiece that doesn't require massive in-focus. The edge does suffer a bit for it, though. I prefer the 22mm AT AF70 in all ways over the 24mm APM UFF if a 2" focuser is available. It's cheaper, wider (70° AFOV, 74° eAFOV), better at the edge, and has a slightly larger effective field stop of 28.4mm. Eye relief and flatness of field is about the same for both.

Except that you're going to want collets (OVL) to keep the eyepieces centered and better aligned than is possible with a single thumb screw (WO).

My neighbor has lights shining up into his trees and bushes at night, as if it serves any useful purpose. I guess they think it looks neat. Sort of like putting LED lights under your car.

Here are my thoughts on them: Rigel QuikFinder can be difficult to find the circles and has slight parallax issues. Small and light. Battery will last 20+ years with no corrosion. Telrad is huge but I never have trouble locating the thicker circles, plus they go out to 4 degrees, not just 2 degrees as with the QF. AA batteries can and will corrode inside, ruining the illuminator, unless changed regularly. RDF is cheapest and gets the job done if all you want to do is put the scope on a target. Haven't used one long enough to declare anything about their battery life. Green laser sight is my preference with my injured neck. Quickest way to put a scope on a target that I've found (1 to 2 seconds). Americans have embraced them while Brits have eschewed them. Just look and listen for aircraft before lighting it up, and you'll be fine.

Probably. SpaceX just launched 60 more on Sunday, so they have probably yet to attain their final orbits and are closely following each other for now.

According to this chart from Ohara, FPL-55 is much closer to FPL-53 than it is to FPL-51: If it is easier to work with and cheaper than FPL-53, then it probably is a win-win all around.

Hmmm. This scope seems to have replaced the TS-Optics Photoline 90mm f/6,5 Triplet FPL-53 APO. Searches for it redirect to this new scope. vs. The new one is about 50 Euros more, slightly faster, no removable segments, has a flimsier looking focus knob, comes with a carrying handle, appears to use collets instead of compression rings, and substitutes FPL-55 for FPL-53 glass. It would be interesting to compare test reports and actual images taken with both. I have the older version. It's quite nice, though I don't know where they get the 6kg load capacity of the focuser from. When I load up mine with a 2" GSO dielectric diagonal and 17mm ES-92 (not even 3kg combined) and point it near zenith, it wants to unwind. I have to tighten up the two focus tensioners (one on the pinion, one on the tube). Perhaps they're referring to deflection? I still don't know why focuser manufacturers they don't use a system similar to the Manfrotto geared central column. The crank axle comes in nearly perpendicular to the rack and is completely impervious to having thrust driven backward through it: I'm guessing they use a worm gear arrangement. Perhaps there would be too much slop for a fine focuser? I don't know about others, but I almost always approach best focus from only one side (that being the lifting side) anyway. If I overshoot, I tend to come back to the other side and creep up more carefully. Once you're at the right height with the tripod crank, you just snug down the column lock which pushes the two flat sides of the column against two bearing pads to prevent any play in the system. Something similar would appear to be applicable to focusers.

So, would putting a 3x Barlow in that f/4 system make the coma appear no worse than in an f/12 scope? That is, do Barlows (telecentric or not) have any effect on coma? I ask because my higher powered eyepieces with strong negative sections (10mm Delos, 9mm Morpheus, 7mm XW, 5.2mm XL, 3.5mm XW) tend to look roughly the same with or without a CC in my f/6 Newt. The same can't be said of my longer focal length premium eyepieces, even accounting for the stronger field curvature without a CC.

I specifically went off and bought used sets of both the Meade HD-60s and AstroTech Paradigms (Starguiders) just to see how good or bad they are and compared them in this thread: If you're used to paying $300 to $500 for a single eyepiece, it's pretty neat to get two whole sets for under $600. I compared them again to other eyepieces in my collection in this thread: If you need to wear eyeglasses due to astigmatism, the HD-60s are the clear winners. If you're price sensitive, the Paradigms (Starguiders) are the clear winners.

Did it require any additional in-focus relative to the eyepiece alone? My GSO CC requires 11mm of in-focus. As a result, neither my 25mm Paradigm (Starguider) or S-W 5-8mm zoom will come to focus with it (I have a very low profile focuser optimized for an undersized secondary). I've read it is anywhere from 10mm to 19mm.

🤔 From the Online Etymology Dictionary: gnome (n.1) "dwarf-like earth-dwelling spirit," 1712, from French gnome (16c.), from Medieval Latin gnomus, used 16c. in a treatise by Paracelsus, who gave the name pigmaei or gnomi to elemental earth beings, possibly from Greek *genomos "earth-dweller" (compare thalassonomos "inhabitant of the sea"). A less-likely suggestion is that Paracelsus based it on the homonym that means "intelligence" (see gnome (n.2)). Popularized in England in children's literature from early 19c. as a name for red-capped German and Swiss folklore dwarfs. Garden figurines of them were first imported to England late 1860s from Germany; garden-gnome attested from 1933. Gnomes of Zurich for "international financiers" is from 1964. I assume you're having a bit of fun with us with your backronym for gnome.

Yes, it stops field rotation. But to quote you above: Neither of these use cases requires the suppression of field rotation in an SCT. For planets, you takes tens of thousands of very short exposures and use software to select the best images, derotate them, and then align them. Since there are no diffraction spikes from spider vanes, you don't have to worry about rotating diffraction spikes between frames as there would be with an alt-az Newtonian. For big Dobs and planetary imaging, folks generally use an equatorial platform to control diffraction spike rotation across frames, at least within one, one hour tracking pass of the platform. Here's an image of the NexStar 5SE with the equatorial wedge raised: That doesn't look stable at all. I've got to think there's lots of flex and opportunities for vibrations to keep ringing through the system. Any sort of breeze could set it to vibrating like a mechanical clock work. It certainly would be useless visually in that mode. Anytime you touched the focuser or bumped the eyepiece, it would take forever to settle again. Compare it to this older C5+ equatorial wedge: That thing looks a whole lot more stable with 3/8" metal plates everywhere. I'd also wager that fork arm is metal rather than plastic. Being equatorially mounted wasn't an afterthought back then.

Are you talking about the NexStar 5SE? If so, it's already fully goto in alt-az, so tipping it with a wedge adds nothing for visual observing except additional vibrations. In pre-computerized goto days, the equatorial wedge was the only way to track with a fork mount. That's no longer true.

28mm RKE in a field flattened AT72ED at f/6 compared to some others in my collection:

So, basically, pick some ancient European tribal name name such as Thuringia, Ostrogoth, Visigoth, Alemanni, Pict, Suevi, etc. and slap it on a telescope sold in Europe? By this reasoning, we'd be getting Koroa, Mohegan, Powhatan, Takelma, Wyandot, etc. branded telescopes here in North America. I guess I better get started trademarking them.

I bought a 127 Mak on an alt-az mount for my daughter to use on camping trips. It's fairly compact.