Louis D

Here's a new 2.5mm to 6mm AFOV group image including my new Aquila (TMB) Planetary II SW 2.5mm eyepiece. Sorry, no new exterior group shot: And here's the new 32mm-42mm AFOV group image including my new Lacerta ED 40mm. Again, sorry, no new exterior group shot:

If you want to stay low cost for maximum TFOV, the Lacerta ED 40mm is nearly as well corrected as the Pentax XW 40mm for a lot less money and weight. I enjoy using it in my f/6 ED and f/6.6 APO refractors. It also does well at f/6 in my Dob.

I've bought two used Synta 127 Maks (Orion and Celestron liveries) for me and my grown daughter, and neither has mirror shift, flop, or even lag when changing focus direction. I have been rather surprised and satisfied by this. The general agreement is that it has about 118mm of clear aperture, or 4.6". With a 2" visual back (now standard on US Sky-Watcher Skymax models), you can get down to about 45x and and have decent wide field views with about 35% vignetting in the outer field which is surprisingly hard to detect visually.

Lucky you. The ones I got from ebay for my 12mm NT4 smell a bit like inner tubes or car tires. I don't know how to predict the smell or lack of it with a particular O-ring supplier.

You may want to stick with the hair bands. Rubber O-rings have a rather strong chemical odor that never seems to go away.

Since the TV Delite eyepieces all focus 0.25" below the shoulder (reference surface), and the XWs focus at the shoulder (pretty sure on this point), pulling the Delite out of the focuser holder 1/4 inch should bring it to focus following focusing with an XW.

Look at it this way, you got quite a few good years in without astigmatism. I've been fighting with astigmatism since I was 14 years old (something to do with puberty changing my eyes). My distance prescription back in the day was only 0.25 to 0.5 diopter off, so it was mostly the strong astigmatism forcing me to wear eyeglasses.

I suppose I could put a restrictive field stop in it so I could see the entire (restricted) FOV. If there was a Morpheus, APM UFF, Delos or ES-92 in that range with 70+ degrees, I might try it. The various 20mm 80 degree Long Perng LHD/LER variations out there might be a workable alternative. However, it would be so close to the the 17mm ES-92 in TFOV, that I'm not sure what the point would be. I also have the 22mm AT AF70, and I can see the entire FOV without issues, but it isn't quite as sharp over those 70 degrees as the 22mm NT4. I swapped back and forth and decided that I preferred the sharper view even if I couldn't see all the way to the field stop. Selling off an eyepiece that comes very close to meeting your needs without a viable replacement seems silly to me. For me, I'd have to go back to using the 22mm AT AF70 knowing it isn't quite as sharp as a former eyepiece I used to own every time I use it. I really want ES to release a 22mm to 25mm ES-92 for this reason.

For sheer wow factor when wearing eyeglasses, I really like my 17mm ES-92. The 12mm isn't quite as well corrected and has a touch of SAEP, so it's a close second. I still greatly enjoy slipping my decloaked 40mm Meade 5000 SWA into the focuser and just panning around the sky to see what's out there on any given night. Its vast amounts of eye relief with no blackout issues and a sharp, low power field makes for a relaxing stroll around the sky.

I'll have to check for that. What I do recall is that stars in the outer 50% of the field turn into beautiful rainbow comets pointing to the center. It's not subtle at all. I always figured it would be a great outreach eyepiece for the under-8 crowd that like rainbows and unicorns. 🌈🦄 One night, I noticed the 12mm NT4 had EOFB all the way to the center. I swapped eyepieces (12mm ES-92, 14mm Morpheus, etc.) to make sure it wasn't just the seeing conditions, but it was real, and it was severe. It isn't noticeable every time I use it, but the potential is definitely there. Only the very central 5% of the FOV was close to normal background gray. The graduation of increasing brightness to the edge was very linear in perceived brightness. It always surprises me that no one else has reported seeing this effect with it. It was not subtle. The outer edge looked a bit like having the full moon nearby. I can tolerate its SAEP mostly because with eyeglasses I can't get in close enough for it to manifest itself very much. Yes, it's presenting more of a Delos to Morpheus sized AFOV, but that's still rewarding. My grown kids and their SOs thought the views through it were terrific during an impromptu star party a couple of years ago after a holiday dinner.

Yes, but notice the damage hasn't spread. That corrector looks to be in no danger of shattering. If shipping wasn't so high to the US (and ENS not removing VAT for US customers in their cart), I'd have a go with it. They're $900 new over here. I seriously doubt it has much if any effect on the image if completely masked off. I don't see any evidence of spalled glass on the primary, either. Compare that to these shattered SCT correctors. What's going to hold the secondary in position in some of these cases?

Yes, there is literally no way to avoid kidney beaning once you are close enough to see the field stop. It's so bad, though, that it is hard to recognize as such. Most folks write it off as a fussy exit pupil instead. You can see how bad they are in my comparison image below: The 14mm Morpheus basically has none.

I'm picturing you like this at mealtime: 😄

A bit off topic continuation (apologies to OP), but here goes: I rarely use Barlows because of parfocality issues, long moment arm balance issues, exit pupil issues, and vignetting issues. This despite the fact that I have five 1.25" Barlows, one 1.25" telecentric magnifier, two 2" Barlows, and a TV PBI. I will tend to put the 2" GSO ED 2x Barlow and TV PBI into the focuser and leave them, simply observing for the rest of the night at 2x. I find it fun to use my big glass at higher powers that way.

Try telling that to stamp, coin, memorabilia, etc. collectors. You'd like Jay Leno since he keeps his extensive antique car collection running and drives them occasionally thanks to his top notch garage team. However, he is very wealthy and can afford it.

You've simply reinforced my conviction to only use Maks for travel scopes at 6" and under if the only other choice is an SCT. Their thick meniscus correctors are practically invulnerable to damage in comparison to an SCT's thin corrector plate.

Agreed about the APM UFF. I'm just not sure if it is reasonably priced in Australia. There are the other brandings of it as well that might be cheaper in AUS $. If the 31mm Luminos is as bad SAEP-wise as my 20mm Meade 5000 UWA, I can understand your friend's decisions to sell it.

The 1.25" Pentax XWs and XLs appear completely flat to my eye as well: I don't have it handy, or any diagrams for it to confirm; but from recollections, my 10mm Delos also appears to also have a (mostly) flat eye lens. I think my 9mm Vixen LV does as well.

Agreed. Doubling aperture diameter to a 12" would definitely be a noticeable step up. I went from an 8" to a 15" Dob. However, soon after, my back was ripped up by an auto accident (not my fault at all), and I haven't been out with it in years. Thus, the 8" gets the use. I ended up going the other direction to see what smaller scopes that I could manage to setup could do.

Please excuse me if it's inappropriate to create and post my own interpretation of someone else's image, but I wondered what I could do with some simple Photoshop Elements edits of the hybrid image above. After some levels adjustments, increased saturation, and selective unsharp masking, I came up the following: I'll admit I'm a sucker for colors that POP!

OMG, those prices are so high compared to USD prices! 😮 I hope y'all are paid roughly 2x what Americans are paid in absolute NZD. At those prices, I would either watch the astro classified ads or go for the most aperture possible with FPL-51 glass. If you go with a slightly longer focal ratio at 80mm, FPL-51 glass should be fine for all but the highest power viewing.

Building on that, try focusing/pointing on/at a fluorescent light fixture, and then put it over the eyepiece to see if you get a spectrum with a few prominent emission lines:

Supposedly, separation is dependent on focal length, but I've found that the same extra 15mm of separation from the diagonal body works fine for both the 432mm FL AT72ED and 600mm FL 90mm TS APO. I removed the extra 15mm for the latter, but couldn't detect any difference visually, so I left it in to keep things simpler. Since the GSO diagonal has a 112mm optical path according to Bill Paolini, that makes the total added separation distance about 127mm as compared to no diagonal/FF. At first, I tried just screwing the TSFLAT2 onto the M48 filter threads of the original diagonal nosepiece. It was clearly too much separation as the field got rather wonky. It does help flatten the field of my 14mm Pentax XL, though. If I pull it out of the focuser a bit as well, it gets a nearly flat field and sharpens up nicely to the edge. I have found that high power, planetary images are better when I remove it because it adds some spherical aberration on axis. It's totally invisible at mid/low powers (think of exit pupils greater than 1.5mm). It really cleans up wide field, low power views and ultrawide mid power views. It's similar to using a coma corrector in a Newtonian. Once you've seen the correction effect, it's hard to go back to not using one. Here are the suggested separation distanced based on focal length: focal length < 450 mm: 128 mm focal length 450-490 mm: 123 mm focal length 500-550 mm: 118 mm focal length 560-590 mm: 116 mm focal length 600-690 mm: 113 mm focal length 700-800 mm: 111 mm focal length ab 800 mm: 108 mm I didn't think it would work for the 600mm FL APO based on this table since the diagonal enforces a minimum separation of 112mm unless I screwed it straight onto the diagonal body, but it seemed no different as compared to using 127mm of separation. Experimentation is the key.

Finally got to taking pictures of the TSFLAT2 attached to my 2" GSO dielectric diagonal this weekend. Please ignore the dust in the second picture. I think it's on the mirror, not the flattener optics. It doesn't bother me or the images, so I'm not about to touch it. The diagonal may say OPT, but it's still GSO made.

If this were a stereo microscopy forum, I'd guess it was an auxiliary magnifying lens to fit over the objectives, although the optics seem a bit small in diameter for this purpose. Any idea how you came to possess it?