Louis D

I strictly use manual scopes. I have Sky Commander DSCs (Digital Setting Circles) on a couple of them for push-to operation. As such, I'm in no position to recommend any GOTO mounts. @Dr Strange thinks highly of the Skywatcher AZ-GTi mount. However, it appears to be out of stock everywhere. I would contact him for further GOTO advice if you are absolutely set on a GOTO mount. Personally, I would probably go the Dobsonian route as others have suggested above and attach a cell phone via an accessory arm as @Dannomiss did in this thread to allow for rough, push-to operation while you learn the night sky using a planisphere app.

Here's a nice comparison of various objective designs done by Vlad Sacek on his Amateur Telescope Optics polychromatic PSF page: As you can see, an FPL-51 triplet has roughly the same correction as an FPL-53 doublet. Also, a moderate focal ratio FPL-53 triplet comes very close to the ideal refractor objective. These two pages on semi-APO and APO refractor objectives and design are also a good read.

Most folks who need to wear eyeglasses at lower powers (larger exit pupils) due to astigmatism can get by without them at higher powers (smaller exit pupils) as this chart from Tele Vue's Dioptrx page shows:

Add trying to get a successful alignment. There are lots of requests on SGL for help getting alignment to successfully complete. This assumes you can see enough bright stars to do an alignment. Due to buildings and trees, I often have difficulty finding enough alignment stars for DSC alignment. Another issue is the often poor reliability of the handsets. They were designed to a low price point which means that durability wasn't high on the priority list during design. Again, I've read plenty of threads about handset issues.

Can you confirm the Luminos's viewing comfort without eyeglasses?

The Luminos is supposed to be fairly comfortable without eyeglasses thanks to it's large eye lens being mounted close to the top:

I measured the usable eye relief of the Panoptic 27mm to be 14mm, which is about how it feels with my eyeglasses. Remember, the design eye relief is measured from the center of the eye lens, and it is deeply concave on this eyepiece and slightly recessed. The usable eye relief is measured from the top of the folded down eyecup. So you've got about 1mm for the folded eyecup, 2mm for the eye lens edge recession from the metal lip the eyecup attaches to, and 2mm of eye lens concavity. By comparison, the Pentax XLs and XWs advertise 20mm of eye relief and deliver 18mm of measured, usable eye relief, so much closer to advertised than the Panoptic. Part of my problem wearing eyeglasses with eyepieces is the bridge of my nose is 14mm deep, so I need a few millimeters more than that to accommodate my eyeglasses. I suppose I could try using a monocle. 🧐

I use a TSFLAT2 in my short refractors to flatten the inherent field curvature of them. Even then, the slight field curvature relative to the APM is obvious. The Panoptic is a fine eyepiece, and there weren't a lot of other options at that focal length at the time I bought it. I now have a wide range of eyepieces between 26mm and 30mm; and the Panoptic sees very little scope time now, mostly owing to its lack of usable eye relief and fairly tight true field of view relative to its competitors.

Although they don't look too good even at f/6 at the edge in my experience, I've found. By f/12, they clean up nicely. I can't imagine what they look like at f/4. I'll stick with my modern widefields for my non-tracking scopes.

I've used my Panoptic 27mm in a variety of scopes for 21 years. It is extremely sharp in the central 50%. It remains very sharp in the remaining 50%, but slight astigmatism and field curvature starts to creep in. It's very minor, but enough I switched over the the APM UFF 30mm over the last year or so. The APM is also significantly more than 10% wider due to having much less edge of field magnification. It is also usable with eyeglasses while the Panoptic is too tight on usable eye relief to use comfortably with eyeglasses. I've also scratched eyeglasses on the Panoptic's exposed eye lens retaining ring.

Look at the field lens end and see if it is near to the bottom. Also look to see if the field stop is visible below it. Most likely it has an internal field stop and is a negative-positive design like many more modern eyepieces. Military eyepieces were often fairly cutting edge for their time because cost was not much of an issue.

Get a Mak to SCT thread adapter, a 2" visual back, and a 2" diagonal and you won't have to duplicate expensive eyepieces on the 127mm Mak.

There are bunch of threads out there on Synta base mods. There's the milk jug washer mod that goes around the central bolt. I would probably replace the factory bearings and bearing surface with whatever you used on the altitude bearings.

Back when I was regularly using my 15" truss Dob, I would use the laser to do rough alignment by getting the return laser beam to coincide as closely as possible with the outgoing laser beam on the secondary mirror (which is plainly visible from the back of the scope) while at the back of the scope. I would then use the Rigel Aline to tweak the collimation incrementally going back forth between the focuser and rear of the scope. This method obviously won't work for a solid tube telescope, though.

I can't figure that out, either. The numbers from a digiscoping calculator indicate that until I get to an 8mm eyepiece, there is no decrease from the camera's f/2.4 native f-ratio for the 127 Mak and 3.5mm for the refractor. And yet, eyepiece for eyepiece, I'm seeing more pronounced SAEP in the f/12 Mak than in the f/6 refractor. However, the effective f-ratio remains f/2.4 for both.

All up, excluding VAT but including shipping, that's well over $250 for the focuser, adapter, and extension. 😱 I only paid $200 for each of my used 127mm Maks. I'll probably take a hard pass on adding one to either of my scopes. Thanks for the information, though.

It's because of the slow f-ratio of the scope combined with the slow f-ratio of the camera. My Galaxy S7 camera is faster and picks up less of the SAEP in comparison. It mostly shows fleeting shadows instead of donuts. In my AT72ED f/6 refractor, some of the worst offenders show SAEP with the slow camera and only the worst of the worst show it in the faster camera. The analogous situation for the slow camera would be daytime, solar, or lunar observing where the eye's pupil constricts significantly, blocking more midfield rays as @Ruud shows quite clearly in this animation: At night, with a fully dilated pupil, SAEP becomes much less problematic. Camera-eyepiece spacing was at the exact point the full field stop came into view. Obviously, pushing in further reveals blackouts, but not of the SAEP type. Also, if you back off, you can avoid a lot of the SAEP as the two Meade MWA 26mm images show, but you lose some of the available field of view. Both situations are shown in another of @Ruud's excellent animations: Notice that it is edge rays, not midfield rays, that are truncated first in this situation. Neither being too close nor too far would show the black midfield rings I photographed. Some folks have complained about "finicky" exit pupils in the NT4s, Meade 4000 UWA 14mm, and the ES-92 12mm. I believe it is undiagnosed SAEP that has been causing it.

It definitely matters at what f-ratio you test them. The NT5 16mm is pretty much immune to fast focal ratios compared to the UO and Celestron equivalents. At f/10, there's much less to separate them, though.

I saw that link. I was surprised they didn't have the SCT adapter in stock since it would be the most common. What did they charge for the custom order when you bought yours?

I took a bunch of photos of the fields of view (FOVs) of many of my 12mm+ eyepieces in my Orion (Synta) 127mm Mak using a 2" visual back and 2" diagonal using an LG G5 phone's superwide angle camera. This scope and camera combination really shows any spherical aberration of the exit pupil (SAEP). I composited together a bunch of the most interesting images with the worst SAEP offenders on the left and the best on the right. Rows are arranged by focal length, although I sometimes cheated and put interesting images on a nearby row to avoid the composite image getting too wide. I hope y'all find this interesting. It might help to explain why some people don't get on well with certain eyepieces. Shadowing is nascent SAEP. Rainbows indicate chromatic aberration of the exit pupil (CAEP). I had difficulty suppressing eye lens reflections on some of the Rini eyepieces, so they look kind of funky as a result. I included them because they are purely positive eyepiece designs that show lots of SAEP.

Check your local library to see if they have a 3D printer available for use by card holders. My daughter used the one at our local library to print things for fun back in high school (8 years ago). I think there was a 4 inch cube size limit and one project per week limit. I would imagine they have an improved printer by now.

As far as affordable UWAs, has any done a head to head between the Nirvana 16mm and the Luminos 15mm? The latter is considered one of the best of that line. I doubt I could use either with eyeglasses, so I'm out for comparing them. I'd be reporting all sorts of astigmatism across the entire field without eyeglasses.

Too bad it's price makes the Noblex 12.5mm look affordable.

Do you have the TS link for the SCT thread adapter? Thanks! 😁

Or just never sell and become an astro hoarder like me. 🤪 I enjoy going back to compare newer acquisitions against older ones. My grown daughter also gets to borrow some really nice eyepieces without having to spend any money at all, so there is that as well.