Louis D

Better than more 100+ F days. We're still waiting for our first July rainstorm. We also haven't been below 98 F all month.

Don't ever get a Newt/Dob, then. You'll have to lean over the scope from the side opposite the focuser to right the image (180 degree rotation). It's not very comfortable and finders tend to get in the way. Since I started on a Dob, I guess I just never let the whole image rotation issue bother me. The left/right flip of a mirror diagonal makes using printed star charts more difficult than a 180 rotation. For Newts/Dobs, you just rotate the chart 180 degrees. For the image flip case, you need to try to look through the page from behind. I suppose with electronic charts today, you just specify the preferred orientation to the software.

I guess mine's defective. I took it apart after noticing it wasn't all that great, cleaned it up, and tried all four orientations of the two lens groups, but even in the best orientation (the original), it's still not all that great.

If only I didn't have such strong astigmatism in my observing eye. I do have a Circle-T Edscorp 25mm which I can use with eyeglasses, but it's not very sharp outside the central area at f/6. I suppose if I had a tracking mount it might be useful. Are the shorter focal length Abbe orthos sharper across the field at f/6?

Peel off or puncture the Celestron logo and you can then access the small screw that the eye guard rides up and down on. Unscrew it all the way with a jeweler's screwdriver, lift off the outer carapace, clean off the grease left on the main eyepiece casing, and store the screw and carapace together in case you ever want to put it back on. BTW, the lens cap won't fit anymore.

And it wouldn't likely come to focus anyway. The optical path through those is pretty long.

Have you gotten it yet? I just realized from reading the various CN reports on it that the presence of AMD or barrel distortion may be squeezing extra TFOV into the AFOV, enough that maybe it shows roughly the same TFOV at a given focal length as an eyepiece with a 75 degree AFOV that has strong pincushion distortion. If it's eAFOV is greater than the 67 degree AFOV everyone seems to be seeing, this might explain the original 75 degree claim from the designers. The 26mm Meade MWA (really a 25mm eyepiece) has an 83 to 84 degree AFOV and a 90 degree eAFOV, which is the same as the 25mm ES-100 which has a 100 degree AFOV. Thus, the designers claim a 100 degree field of view since it sees the same TFOV as a competitor's 25mm 100 degree AFOV eyepiece. Convoluted yes, but I can see their reasoning. The Meade just gets there with barrel distortion instead of the ES's pincushion distortion. I guess we need someone to measure the APM SZ's TFOV at a few focal lengths to back into the field stop diameter after taking the scope's focal length into account.

I don't see a diagonal in your photo, but I do see an inline image erecting assembly. I believe it uses Porro prisms like a binocular, so no spike on bright stars like an Amici erecting prism diagonal.

I can always tell when I have the camera at the right spot for my AFOV images because the field stop pops into view and going any further inward produces blackouts. Of course, if there's massive SAEP/CAEP in the eyepiece, or if there is no distinct field stop, this complicates matters for me taking my images. I then have to find the best distance that represents what the eye sees.

So most are very close to a pound. That fits in nicely with Pentax XW and Delos weights.

It looks like you haven't gotten the camera lens in close enough to take in the actual field stop. As you say, you should see a thin blue line just inside of the blackness of the actual field stop. You may not be getting your eye in close enough, either. Make sure you don't have the included eye cup extender on the eyepiece. Also, make sure the eye cup is fully folded down when wearing eyeglasses.

I've not read reports of this issue with the 17.5mm Morpheus, but anything's possible. Try to take a picture through the eyepiece during the daytime using your cell phone's wide, or better yet, ultrawide angle camera. In my experience with slow scopes like your SCT or my Mak and an ultrawide angle phone camera, you'll get a rainbow effect if you've got true ring of fire which is actually chromatic aberration of the exit pupil (CAEP). You can see it below in the 30mm ES-82 and 26mm Meade MWA Easy images below.

Remember the Zhumell Z100 100° eyepieces in 9mm and 16mm focal lengths? IIRC, they were closed out for around $100 each at the end of their stock run. I'm not saying they were well corrected, but they were cheap for a bit.

I prefer rubber O-rings to parfocal rings because they won't create dimples in the insertion barrel and don't have issues with tightening on the edge of undercuts. This is the case with my 12mm NT4 which needed 20mm worth of 4mm thick O-rings. The last one is riding on the lower slope of the undercut. Check ebay for O-rings.

The Meade 5000 Plossl/SWA/UWA and Celestron Axiom LX/Luminos are all famous for having bulky outer coverings that can be removed to make them lighter by about 1/3rd and slimmer.

Right. Perhaps with exotic glass types and aspherical surfaces, one could achieve the latter two criteria while losing the first. Of course, it they could sell millions of them like smart phones, the price would come down dramatically due to economies of scale. If only 300 to 1000 iPhone 13's were made, as is the most likely case with the 26mm Meade MWA, they would be astronomically expensive (think hundreds of thousands to millions of dollars apiece to recoup R&D, wafer mask, and initial tooling expenses alone). There just aren't enough amateur astronomers in the world to bring down the cost of exotic eyepiece production, so we'll likely never see them come to market. Maybe some military will pay the tab for a short run of exotic eyepieces that we can then buy in 30 to 50 years time when the spares are surplussed due to obsolescence.

If you scroll down to the bottom of the posting by Ernest, he tests the 26mm Meade MWA. Above that, he mostly rags on my report as being methodologically flawed because I use comparative analysis against my other eyepieces to arrive at photographically derived central and edge focal lengths as well as AFOV. He never even tries to put a value on the edge radial focal length. I take all the claimed and measured values, run a best fit mathematical analysis on the data, come up with a coefficient, and apply it across the board. With 70+ data points (eyepieces), the fit is pretty darn good. For the 26mm Meade MWA, central focal length is 25.1mm while the edge radial FL is 21.2mm, so not much variation. With my method, I can even measure/calculate the easy and full AFOVs that Ernest doesn't both to measure. They are 79.4° and 83.3°, respectively. Thus, you don't lose all that much AFOV due to SAEP by pulling back to 18mm of eye relief to avoid 95% of it. Ernest goes on to nitpick that the eyepiece doesn't deliver 100° AFOV, but 83.6° (really close to my measurement) instead: Claimed to be 100 degrees with an actual angular field of view of just 84 degrees! The audacity of Meade is amazing. Even the effective field of view (across the aperture) is only 90 degrees. That is, it is never a competitor to the 25 mm 100-degree from Explore Scientific. However, he fails to grasp that it delivers the same TFOV as the 25mm ES-100 since both have a 41mm field stop, but with distortion opposite that of the ES-100. Both have an eAFOV of 90° based on this common FS value, so both show the same TFOV. They're basically a true competitor, just with opposite distortion. Thus, the Meade is saying it delivers the same TFOV experience as its competitor's product in a deceptive way by claiming 100°. Ernest even defends the 5mm and says below his review of this distortion difference yielding the same TFOV as others' 100° eyepieces: 'MWA in this sense are more "honest" eyepieces. And attacks from some observers are explained by a misunderstanding of basic optical concepts.' And yet he falls into the same trap with the 26mm! He needs to be consistent in how he applies his reasoning. I also totally don't get his results at f/7: In a telescope 1:7 Strong defocus at the edge of the field of view due to curvature In the zone, a clearly visible halo of curvature slightly shifted to the side of the edge of the field of view At 50% of the zone, the images of the stars are already noticeably "snotty" All is well in the central area At f/6 and f/6.7 in my field flattened refractors (ED and APO, respectively), I can't detect more than the tiniest defocus center to edge, and my eyes don't focus anymore to accommodate field curvature, so I would see it, but I don't. Also, the stars are basically pinpoint to the edge. It's barely worse than my 22mm Nagler T4 in this respect. His words make it sound like it has an edge performance level similar to a 26mm Orion Q70, which it most certainly does not. In fact, it is this lack of field curvature and lack of edge astigmatism that has made it grow on me despite its warts (strong SAEP and barrel distortion).

Here's my take on the 26mm Meade MWA that no other branding seems to have ordered: It's flawed, but it kind of grows on you. I'm keeping mine as a rather unique eyepiece that is no longer available. It's sort of a 25mm (it's true focal length) Morpheus with barrel distortion and SAEP. Until Baader markets a 2" Morpheus in that range, it will have to do.

I think we can rule out KUO (Kunming United Optical) that makes the well regarded APM/Lunt/Stellarvue/Myriad/WO/Astro-Tech/etc. XWA 100 degree eyepieces. Why would they also sell a poor, non-competitive, false 100 degree line of eyepieces? We can probably rule out JOC/Explore Scientific/Bresser since they also have a bonafide 100 degree line of eyepieces (ES-100). That would leave Long Perng (I doubt it having never seen these on their website) and some others. If I had to guess, it's the same company making the Celestron Luminos and its bretheren since both are flawed interpretations of other eyepiece lines (i.e., Ethos and Naglers) with overstated eye relief figures. However, no one seems to know who is making the Luminos line, either.

They're reviewed here in Omegon Panorama II livery:

I had totally forgotten I'd posted that almost exactly 3 years ago. Good catch!

More than likely another branding of the Meade MWA line-up:

Perhaps a 20mm XWA from APM/Lunt/Stellarvue/Astro-Tech/etc? You might gain 5mm in field stop size. There's always the TV 21mm Ethos as well.

The problems with Dioptrx are It won't fit all eyepieces Still requires about 15mm of usable eye relief, so not a panacea for astigmatism sufferers Prevents view swapping unless you both have the same amount of astigmatism (you can simply adjust the angle by rotating it if it differs between observers) Requires one per eyepiece unless you like messing about in the dark swapping it across eyepieces Still leaves you blind when looking up to the sky from the eyepiece The correction angle changes depending on the altitude of the object when using a Dob requiring retuning between objects. Using long eye relief eyepieces with eyeglasses pretty much eliminates these issues except that eyepiece choice becomes a bit more limited due to needing 17mm to 18mm of usable eye relief.

Perhaps swap the 18mm and 24mm UWAs for a 20mm XWA from APM/Lunt/Stellarvue/Astro-Tech/etc?