Louis D

I would think you would only see the specs when lunar or solar viewing.

The wider field allowed by using 2" eyepieces more than makes up for the focal length extension to somewhere around 1700mm to 1800mm. I also didn't notice any increased spherical aberration at higher powers. People who mount a focuser on the rear threads have the same focal length extension issue, and I haven't heard them complaining about it on here. If your 127mm scope didn't come with SCT threads already, you'll need this adapter and a 2" visual back. There is vignetting in the outer field, but it isn't very noticeable visually. What is noticeable is when bright objects pass the edge of the rear baffle, you get an oval shape that grows larger the farther off axis that bright objects gets. Just recenter it and it goes away. You can judge from these images I took through my 127 Mak demonstrating the additional field gained by using a 2" eyepiece versus a 1.25" eyepiece and the vignetting. I realize now I didn't use a 1.25" visual back for the first image, so it might be about 12% to 15% wider with one. At 85% center to edge, I sampled the luminosity of the lower image to be 65% of the center luminosity.

For visual, if you're mono-viewing (one eyepiece), and you don't have astigmatism, you can probably observe with your eyeglasses removed because you can focus out your distance correction. As such, you can use eyepieces with limited eye relief. If you have astigmatism, you'll probably need eyeglasses or possibly a TeleVue Dioptrx to correct out your astigmatism, depending on how strong your astigmatism is and what exit pupil your telescope/eyepiece combination is operating at. As such, you'll need to use eyepieces with at least 15mm to 20mm of eye relief to accommodate either your eyeglasses or the Dioptrx. In either case, since you're only using one eye to observe, the other one won't be looking at much. If it still bothers you, you can cover the non-observing eye with an eye patch. If you're binoviewing (two eyepieces), you'll need your eyeglasses since your eyes focus at different distances.

Low cost R&P focusers generally don't have any adjustment mechanism(s) to reduce the wobble you're experiencing. Shimming the tube is generally the best workaround short of upgrading the focuser.

I also have grown trees in my backyard limiting my view nowadays. As a result, I plan my observing around what is visible to the south in the clear patches. As the night moves on, I observe new targets that come into view. For instance, to observe Jupiter and Saturn recently, I had to observe between 11pm and 1am. First was Jupiter until Saturn cleared the trees and then Jupiter went behind a house after a bit. I really miss my northerly views the most. I'm looking at getting a second home for getaways and retirement that will have darker skies and better sight lines.

Did you find that them to actually be 100° eyepieces? I have the Meade MWA equivalent in a 26mm, and I measured it to be around 78° to 83°, depending on how much SAEP you can tolerate. As such, it's basically in the same class as 82° eyepieces.

More specifically, it's based on the Rayleigh criterion. Wikipedia has a good article on angular resolution.

Depends on the criteria used. If you're splitting double stars and just looking for elongation rather than a clean split, then that allows for a claim of higher working power. Realistically, most beginners need not concern themselves with such technical esoterica. John has pretty much nailed what is typically the maximum working power for your scope and observing conditions. If on the other hand you were observing from certain coastlines, deserts, or coastal mountain tops with excellent seeing conditions and are using a 16" to 30" Dob, it's quite possible to successfully use powers in the 400x to 1000x range.

I would stick with the GSO/Revelation diagonals because the WO (Synta?) and its variants have a field stop of sorts at the bottom of the insertion barrel that vignettes widest field 1.25" eyepieces. Since I use mine for binoviewing with 22mm clear aperture binoviewers, this doesn't matter to me, but it might to you.

Totally missed that. 🤣 It's just one of those days.

With the eyecup removed, close to 15mm.

Don't most people report the GSO 2.5x to be closer to 2.2x?

Remember, you still need about 15mm of usable eye relief for the Dioptrx to work well.

The old Meade 4000 UWAs were quite good. The Meade 4000 SWAs were equivalent to the Tele Vue Wide Fields (better than an Erfle, but not as good as a Panoptic), and the original made in Japan Meade 4000 Super Plossls in smooth side were excellent, having been made by Towa as a 5 element design. If you can find these used at good prices and in good condition, they're quite decent performers. The modern Meade 4000 series only refers to their Super Plossl line as far as I know and are simply 4 element symmetrics that are little different from all the other Plossls coming out of China. I would get the GSO/Revelation Plossls from Taiwan due to better consistency from sample to sample at a better price. It's quite likely the Dioptrx fit on the modern Super Plossls, but they also fit on most Plossls out there with removable eye cups.

Dioptrx still need about 15mm of usable eye relief on an eyepiece to work well. It fits on eyepieces with an eye cup lip of about 41mm to 44mm in outer diameter. This is assuming the eye cup is removable. Many non-TeleVue eyepieces have an M43 top thread once the eye cup is removed. Then it's just a matter of it's tall enough for the Dioptrx to cam down onto it securely.

I've got the 7mm XW and 5.2mm XL in an 8" Dob and tend to use the 5.2mm more. However, given your longer focal length, the 7mm would probably make more sense. You could get a 5mm BST Starguider as temporary stop-gap to see if you need that focal length as well later on.

If you go to a wider apparent FOV (AFOV) while maintaining the same eyepiece focal length, you'll see a greater true FOV (TFOV) without increasing sky brightness which does increase contrast and makes it easier to spot faint fuzzies. That's why the 21mm Ethos is more desired than the 31mm Nagler T5 which is itself more desired than the 41mm Panoptic (aside from the desirability of wider and wider AFOVs). Each step yields slightly less TFOV, but the sky darkens noticeable at each step as well. Alternatively, when using nebula filters, the lower the power, the larger the exit pupil, the brighter the nebula appears per unit area. Since the filter blocks most of the light pollution, the contrast get higher at lower powers.

Then you need to buy eyepieces with longer eye relief like Pentax XWs, Delos, DeLites, Morpheus, Vixen SLVs, etc. Many long focal length eyepieces naturally have long eye relief. If you use them with a Barlow or telecentric magnifier, you can get to higher powers while maintaining or even extending the long eye relief.

Like the original smoothie Meade Super Plossls and 8-24mm zoom, the older, Japanese made items are better apparently.

I read on CN where someone resorted to using a Starizona reducer to get decent images at the edges with their SCT after trying many standard reducer/correctors. Perhaps you got really lucky visually?

Have you tried unscrewing the back cover plate to see if there's any adjusting screws hidden underneath? Apologies if you've already tried this.

Nope. You'll get all sorts of vignetting. A 32mm Plossl is about the max when using a reducer.

It's not like they are an international, official naming body; so who cares?

I recommend putting Sorbothane pads under each tripod foot to dampen the vibrations in short order.

Twist the eyecup all the way down and try using the 1.25" eyepieces between your eye and the eyepiece. You should be able to hand-hold them and slide them into the light path.