Louis D

It could very well be the eyepiece appeared to make the star field appear wrapped on a tennis ball and yet have no field curvature. Stars appearing to be wrapped on a ball is a form of distortion. The field appears curved onto a ball, but that does not mean it has a curved field. Curved field means that the field of focus is not flat center to edge. Stars focused in the center get progressively blurrier toward the edge, regardless of whether they appear wrapped on a ball or not. Did stars stay nice and sharp center to edge as they traversed the apparent ball shape? If so, it had a flat field, not a curved field, with distortion.

They're made by Long Perng (Taiwan company, perhaps with mainland suppliers).

Be glad it didn't shear off completely in the threaded hole. That is what happened to me with one of the two thumbscrews in my GSO CC. Apparently, they use pot metal instead of tool or stanless steel for their screws. I swapped out the remaining good screw for a cap head screw made from tool steel. I have yet to extricate the stuck bit of screw from the other hole. I recommend swapping out all GSO supplied thumb screws immediately upon purchase for high quality tool or stainless steel cap head screws.

Just remember to turn it off during image capture, or you'll just get a green fuzzy blob from the laser scatter at high magnification. It makes aligning them with the eyepiece super simple, though.

A C8 does show softer stars than an 8" Newtonian with coma corrector with its much smaller secondary obstruction in my experience. It's one of the reasons I went with an 8" Dob over an 8" SCT. I have never looked through an 8" refractor to make that comparison. In general, smaller APO refractors show even tighter stars than low obstruction Newtonians in my experience. However, you've traded light gathering and compactness for this.

Jeff Davis County, Texas, which includes both the McDonald Observatory and the Prude Ranch (home of the annual Texas Star Party), Fort Davis, and the Davis Mountains has very strict lighting regulations to preserve the night skies there. Streetlights are flat, deep red paddles that I've never seen elsewhere. Homeowners, businesses and ranchers all work together to keep the skies pristine out there. At night, it's eerie in downtown Fort Davis because business signs are dim and many stores have blackout shades to prevent light from escaping their interiors.

Yes, that's basically correct. Here's my post on the subject from 2016: No one on SGL knows for certain who makes the Luminos eyepieces.

They're an older line from 10 to 15 years ago. They're optically the same as the Omegon Redline SW, Astro Tech AF70, Olivon 70°, SkyWatcher SWA 70°, and several other brandings. The 22mm is excellent, the 17mm is pretty decent, the 13mm has loads of edge chromatic aberration and EOFB, and I have no personal experience with the shorter focal lengths. The 32mm is reportedly an Erfle or Konig, and as such, nothing special correction-wise. They have plenty of eye relief for eyeglass wearers once you screw off the rigid eye cup. With its 43mm thread up top, you can fit it with a Baader Morpheus eye cup if you like.

As I said above, you'd probably like the 40mm Pentax XW at 24.7 oz. (700g). Has anyone done a comparo between the 40mm Pentax XW and the 42mm Vixen LVW since both are relative lightweights at this focal length?

I only clean the eye lens when it is apparent that shifting a star or planet around the FOV shows some areas are distorted due to smudges/gunk, or I accidentally put a fingerprint on it.

Is the field stop well above the insertion barrel requiring lots of in focus? 48mm is the outside diameter of the insertion barrel, so it must be quite a trick to make the insertion barrel wall as thick as foil.

The 40mm Pentax XW has a measured 46.3mm to 46.5mm field stop, so also about as wide as possible with the field stop within the insertion barrel. It's not quite as sharp to the edge as the 40mm ES-68/Maxvision/Meade 5000 SWA, but's it's a lot lighter and more ergonomic for both eyeglass wearers and non-eyeglass wearers. Why do you want to go up to a 50mm eyepiece? Are you planning on using it in a slow scope like an SCT?

Just huff upward holding the eyepiece above your mouth, so you're less likely to get saliva on it.

Post images of the lenses and spacers. A lot of times, there's only one order that works, and it comes down to which way to flip individual lenses that are nearly symmetrical. You end up trying both ways to see which orientation provides the better image.

Also known as bar clamps. 🤨 I'm not sure what the preferred name is here.

Back on topic, I usually try new eyepieces with at least one of my Barlows to see if it works at all. Widest true field eyepieces for a given barrel diameter tend to vignette somewhat with non-telecentric Barlows. Long focal length Barlows tend to outperform short focal length Barlows, given the same number of elements. An advantage of Barlowing standard long focal length eyepieces over using a standard short focal length eyepiece by itself is the better eye relief in the former relative to the latter.

Never heard it called a G-clamp. Everyone in the US refers to them as C-clamps. I guess we just ignore the threaded rod part and focus on the casting part. Do you Brits call the curved drain pipe under a sink a P-trap or a U-trap or maybe a J-trap or something else entirely? I'm not talking about an S-trap either. See below:

I was just pointing out that all is not lost even if it is an FPL-51 triplet. Yes, it was certainly misleading when it was labelled as an FPL-53 triplet, but FPL-51 triplets can be pretty decent performers.

Because you don't have to contort your neck, back, and knees to look up and through anything with a laser sight (which work better for me than laser pointers). I suppose if you could mount the RDP about 7 or 8 feet high or more so you don't have to crouch, that would work as well, but it would be in the way on that long of an arm, and the window would be tiny at that distance. Wait until you've had multiple neck and back injuries along with arthritis, and we'll discuss again the merits of unit power finders over laser sights/pointers. Until then, I'll take my near zero chances of lighting up an aircraft cockpit momentarily with a GLS/GLP over struggling to get my scope in the general vicinity of the target with an RDP.

Has no one on SGL ordered one of these?

Looks like stupid laser pointer use isn't limited to this side of the pond:

So, it should give color correction similar to an FPL-53 doublet, but with longer cool down time. Compare lines 63 ad 64 along with 42 and 44 below.

Markus confirms sub-70 degree AFOV and has removed the 75 degree claim from the website. He has offered refunds to those who pre-paid their pre-orders if they want to go that route. Markus's mea culpa. Based on CN report so far, aside from the nearly constant ~67° AFOV, the main negatives found are its RD (which is great for terrestrial viewing) instead of having AMD and EOFB (which even high end zooms suffer from). Eye relief seems good for eyeglass wearers, it's sharp to the edge even in fast scopes, very nearly parfocal throughout its range, and it's comfortable to use with no appreciable SAEP. 1.25" usage may be limited by available in-focus on a particular scope. This is not an issue in 2" usage. The zoom motion is apparently quite stiff. Still no confirmation on Dioptrx compatibility. It sounds like a winner for spotting scope usage (apparently what it was designed for). It might be a bit less of a winner for astro usage.

House break-ins seem quite rare around here. I wonder if it's because Texans are so heavily armed, and the Castle Doctrine gives them carte-blanche to shoot to kill anyone in their house who doesn't belong there? Outside the house, it's a lot more fuzzy if you can shoot to kill to protect property or even lives, so burglars are unlikely to get shot burglarizing cars or sheds, so cars get broken into all the time around here. Burglars also hitch up to cargo trailers and steal them all the time as well. I've lost track of the number of Boy Scout trailers that have been stolen along with all their camping gear from storage on church grounds. They can be hitched up and gone in well under a minute.

Can you post a direct link to the review related to these ultra low power binos? I couldn't find it on that website.