Louis D

Well, here's an actual photo Markus posted recently on CN of the eye lens end: I'm going to say that the M43 thread is under that knurled ring rather than under the rubber eye cup. As such, the Dioptrx might not be able to reach the M43 thread because of the upper M37 thread. Here are images of the Sky Rover version: That seems to confirm my suspicion that the eye lens (27mm) is way too small to accommodate both a 75° AFOV and 18-20mm of usable eye relief at the same time. You'd need about a 36mm eye lens as in the Morpheus, not 27mm as here, to do that. It also confirms my suspicion that the M43 thread for Dioptrx is below the M37 thread, rendering it useless as is. Perhaps if you screwed an M43 to M37 step down ring onto the M37 thread or a Hyperion / Morpheus® M43 extension to the M43 thread it might work. I'll bet no one at the factory actually tried to put that CN member's donated Dioptrx on it to check for compatibility. It also confirms the 2" barrel is nonremovable. This means a lot of in-focus will be required for 1.25" usage. That could be a deal killer for BV'ing folks running out of in-focus. Finally, here's the manufacturer's animated gif looking through the eyepiece while zooming showing constant field (good) and slight SAEP (kidney beaning): Rectilinear distortion looks well controlled, and edge sharpness appears good as well. Perhaps it would make a good travel eyepiece for me for nighttime and terrestrial usage as long as I don't mind panning my eye around the field while wearing glasses. Another image in that thread show the price at 2099 Chinese Yen which equates to about $318, so not much cheaper than APM's $349 price.

My bushy eyebrows get in the way of anything poking up that high. I've got Neanderthal brow ridges pushing them out even further. Bummer. My prescription changed yearly for about 4 years in my mid-40s when presbyopia set in. Then, it settled down and I haven't had a major shift in a decade since. That's not to say it won't shift again someday. I'm currently wearing 8 year old bifocal glasses because a nose pad came off my 7 month old pair of daily wearers. I'm heading out to my eyecare place today to get it replaced. The prescription is basically the same between the two, and I adjusted in minutes. There's always fudging of that last quarter of a diopter as far as which one works better, especially when the phoropter goes down to an eight diopter, so you have to go either up or down an eighth for lenses if you land between them for best correction. I generally get one new pair of bifocals a year because they're completely paid for via work insurance. This last time, I got a pair with magnetic clip-on polarizing sunglasses. That way, I get polarized bifocals for cheap. My insurance won't cover polarizing lenses or tints, but they will cover clip-ons. I buy my reader, computer and astronomy single vision glasses from EyeBuyDirect for a tiny fraction of what my eyecare place wants. The brick and mortar store has got massive overhead to cover (building, labor, etc.), but I figure I do my part getting a yearly eye exam and pair of glasses to support them. In fact, I am wearing computer glasses I bought 5 years ago as I type this. Absolutely no reason to replace them that I can find. If I could get oblong frames to custom fit within my eye sockets like two monocles, that would be ideal for eye relief and full coverage. Instead, pretty much all frames sit fully in front of your eye socket which is an eye relief and coverage killer for Neanderthals like me. Yes, I could go with contacts, but I've read that toric lenses tend to spin while hunched over an eyepiece, ruining astigmatism alignment. That, and I'm outside exposed to year-round eye irritants here in Texas. There is no off season for pollens here.

If the quartz is laid down via vapor deposition on a substrate like a coating, it can be flat to the atomic level because it is crystalline, but I doubt that's how it would have been manufactured. I think it just means it's pure silica amorphous glass.

If nearsighted, does his eye focus behind his cornea?

Makes me glad I bought an Astro Tech 72ED. It has plenty of in focus left with a GSO 2" dielectric diagonal. Why would SW sell a scope with a 2" focuser than doesn't have enough in travel to accommodate a 2" mirror diagonal? You might try a 2" prism diagonal to save a few millimeters of optical path length: Approximate direct measure of the diagonal light path (millimeters)

Not only that, but higher index lenses have more dispersion, so stars at the edge of the field spread out into rainbows more obviously. I get the cheapest base pair of lenses and live with the slight extra thickness. This isn't an option for everyone. My middle daughter has 5.0+ diopters of distance correction, so even high index lenses look thick. She mostly wears contacts as a result.

I don't like how coatings peel away at the edges of lenses over the years. It looks terrible and can't be good optically.

It certainly works better to take off my glasses with short eye relief eyepieces, but unless I'm down below 1mm exit pupil, stars are spiky and planets lose some detail. 2.0 diopters of astigmatism make stars super spiky at 2mm and higher exit pupils. Dim stars also just disappear altogether kind of ruining the experience. What's the point of using expensive eyepieces if the image is terrible looking? I'd have to wear contacts to use Ethos eyepieces, but I already have enough issues with scratchy, dry eyes.

Your left eyeglasses look about identical to my daily wear pair. I went with a larger, squarer frame for astronomy rather than rounded. They still cut off the top and bottom of the field in my ES-92s, but are fine left to right.

It makes sense you can't truncate from distance A' to D while keeping a triangular profile to the entire enclosure. If you did, it would look more like a GSO dielectric mirror diagonal along the hypotenuse:

So, to achieve the same clear aperture as a simple right angle prism diagonal, the Amici prism diagonal version would need a 71% larger enclosure by diameter to contain the larger prism?

My eyepiece images thread. I've read that the 24mm and 41mm Panoptics were the last to be introduced and that Ethos/Delos/Delite designer Paul Dellechiaie tweaked the design to improve it a bit. This had the side effect of reducing both the physical size and eye relief of at least the 24mm version to make it binoviewer friendly. As such, it has 15mm of design eye relief, which probably equates to about 12mm of usable eye relief at most. For reference, my 27mm Panoptic is spec'ed at 19mm ER, but I've measured mine to have only 14mm of usable ER. It is so tight to use with eyeglasses that I've scratched an eyeglass lens on the eye lens retaining ring. I've calculated that it can have no more than 18mm of design eye relief given its 25mm eye lens diameter. I'm guessing the eye lens has at least 1mm of concavity to bring it up to 19mm ER. I've since replaced it with the 30mm APM UFF in my A-Team case which is easily used with eyeglasses. The Panoptic might be a tad bit sharper in the center, but it has a bit of field curvature and edge astigmatism/chromatism. The APM is flat of field and has no edge aberrations that I can detect. The Meade 5000 SWA/ES-68/MaxVision SWA eyepieces are pretty clearly Panoptic clones. Al's patent (US4525035) expired before they were introduced (Jan 5, 2004), so it was completely above board to do so. I think the clones use lower cost glass types to keep costs down relative to Panoptics because their correction isn't quite up to Tele Vue standards in fast scopes.

Good sleuthing. They're also sold as TPO brand by OPT (get it?) in the US. I think one of mine has this branding if I were to check it.

The APM UFF 24mm and it's optical identical brethren under other brandings has enough usable eye relief (17mm) to use with eyeglasses and is well corrected across the field. The last 5% has some vignetting issues resulting in a somewhat soft field stop due to the design being pushed a bit far (a 27.3mm to 27.5mm field stop in a 1.25" barrel, depending on where you declare the edge to be). The eye lens is 37mm in diameter, but it's recessed quite a bit to avoid having too much usable eye relief. It views a bit tighter than the 9mm and 14mm Morpheus and the 3.5mm, 5.2mm, 7mm, and 14mm Pentax XL/XWs all of which have 18mm to 20mm of usable eye relief. It's enough I can't hover but must instead lightly touch my eyeglasses to the folded down eye cup of the APM. It views the same as the 12mm and 17mm ES-92s in that respect for reference. The APM's 63° AFOV has way less edge distortion (about 15% extra radial magnification) compared to the MaxVision/Meade 5000 SWA/ES-68/Panoptic style edge distortion (43% to 47% extra radial magnification). I actually prefer the APM's presentation despite it appearing narrower in AFOV. In fact, it's eAFOV (effective AFOV for accurately using the TFOV=AFOV/Mag equation) is 66° which is basically the same as the Panoptic and its variants. It's really the only option out there at 24mm with that sort of eye relief at 66° eAFOV in a 1.25" barrel. Here's an image comparing various eyepieces in my collection around 24mm taken through a field flattened f/6 72ED refractor for reference:

They're stored across 8 cases. I mostly use those stored in my A-Team case which receives upgrades over the years as new and better eyepieces become available. I hold onto the eyepieces that are replaced for comparison purposes. I'm not short of cash and have plenty of storage space, so I'm not in any hurry to sell them. Many are long since discontinued and are difficult to locate should I become nostalgic to look through them again. I keep these retirees in separate cases. Some are special purpose, such as for binoviewing and are in a separate case. Some are affordable kits I bought for comparison and review. I've passed these along to my daughter to use. She's figuring out which she likes best. As she progresses, I'll probably loan her some of the retirees that used to be top of the line eyepieces in their own right. Some eyepieces were packaged with telescopes and have no resale value at all, so I keep them for comparison. I enjoy documenting hard measurements of them to better understand how eyepieces differ from each other and from their manufacturer specs. I compare myself to musicians who have 40 or more versions of their favorite instrument such as trumpets and guitars. They usually represent various eras and styles and have different characteristics and qualities that make each special.

I'll just be interested in how much usable eye relief it has. I have to unscrew and remove the twist-up eye guard on my Celestron Regal zooms to use them with eyeglasses. They have about 13mm to 16mm of usable eye relief when used in that configuration. Given its 45° to 63° AFOV and 26mm eye lens diameter, it should have no less than 21mm of design eye relief. I don't have high hopes for the claimed 18mm to 20mm ER for this "super zoom" at 75° with what appears to be almost the same sized eye lens since both have an M37 thread around it. I'd like to be pleasantly surprised, but I'm not holding my breath. For comparison, my APM Hi-FW 12.5mm (which looks to be made by the same company as the APM Super Zoom) has 18mm of usable eye relief with the eye cup flattened after removing the knurled top ring. That's with its 36mm eye lens and measured 80° AFOV. APM claims 23mm of eye relief for it. So, 5mm overstated. That could mean the ASZ (APM Super Zoom) has 13mm to 15mm of usable eye relief, which I could totally believe. If that's the case, I won't be interested in getting one for mono-viewing. From the claim it focuses 12mm inward of the 13mm Ethos, that puts its focus plane 5mm above its reference plane (shoulder), thus needing 5mm of in-focus (about what is shown in the diagram below, I just can't make out the digit clearly). That I can live with if true. But, according to the diagram below, that's in 2" mode. Unless the 2" skirt is removable, it will require 32mm of in-focus in 1.25" mode according to that diagram, which could be an issue for some scopes or for reaching focus with binoviewers.

Here's a webpage describing the gluing process in detail with images. Just remember, if you ever need to clean the mirror, either the cell and mirror get cleaned together as a unit, or you have to cut the glue, clean the mirror (including glue residue), and re-glue the mirror to the cell.

Have you tried focusing straight through with an eyepiece, both with and without the Barlow, to see which way and how much it shifts focus? Those results should carry over to the imaging setup.

It comes down to profitability. The absolute profit on a $3000 motorized focuser is much larger than on a $400 manual focuser, so you concentrate on the former since the labor involved is similar for both. GM and Ford have done the same with vehicles. All US manufacturing is of high profitability full size pick-up trucks and SUVs. Most of the smaller vehicles are made outside of the US to take advantage of lower labor costs. Apparently, MoonLite didn't want to shift production out of the US to cut costs on manual focusers, so they stopped making them altogether.

Give it first (and possibly last) light and let us know. Nothing ventured, nothing gained.

Yeah, laser pointers/sights are highly frowned upon here in SGL land, so I quit bringing them up quite a while ago. As someone with a bad neck and back though, I'm right there with you on using them. I still have my Telrad, QuikFinder, and RDF, but for most usages, the laser gets me there quicker and painlessly.

I might get rid of my 20mm Meade 5000 UWA due to its really short eye relief (12mm). If my daughter wants it, I'll probably pass it along to her first, though. It's a very sharp eyepiece if you can get past the eye relief. Even with my eyeglasses removed, I have difficulty taking in the entire FOV and have to be careful blinking to avoid putting eyelash goo on the eye lens.

Since the Tele Vue Nagler T6 series is $14 cheaper in the US than the Vixen SSW series, and does not suffer from SAEP, I would have just bought the TV NT6 series to start with. I don't understand why the SSW costs more than the NT6.

Clean off the dust and see if you can do some basic star testing with the remaining reflectivity to get some idea of it's figure. If one or the other mirror is completely hazy, I guess you're out of luck on that front. These scopes really contributed to Dobs being written off for use only as light buckets for DSOs rather than as serious planetary observing tools as well. Also, the mechanics were pretty crude as I recall. FWIW, I haven't seen one at a US star party in at least 20 years. Some were converted to truss Dobs after having their mirrors refigured and recoated.