Louis D

Looks like a slightly bigger version of my Astro-Tech 72ED.  I use mine for all of my indoor eyepiece testing, so you've probably already seen plenty of those images. 😁

Even with my new Planetary II 2.5mm eyepiece, red/green fringing on the planets was very muted.  I was able to discern low contrast details, and high contrast images like the moon and Saturn's rings looked fantastic and color free.

Since your scope will be faster and larger in aperture, the color correction will be slightly worse.  I would hope the lens figure is just as spot on as mine is.

Now that I think about, my favorite eyepiece is whichever one is yielding the best view of an object at any given time. 😉

58 minutes ago, Don Pensack said:

And buyers who buy from out of the state pay no sales tax on the purchase.

Wrong.  Ever since the Supreme Court's South Dakota v. Wayfair decision in 2018, most states are requiring retailers anywhere in the US to collect and remit sales tax.  Retailers outside the US seem unaffected, however.  I believe this is mostly due to a lack of state enforcement power on international sales.

Rigel Systems makes a series of astro flashlights.  One of them might meet your needs.

51 minutes ago, Don Pensack said:

Hundreds and hundreds of reports on various eyepieces show that SAEP is less noticeable in smaller exit pupils.

I think it's because the same curve with a smaller width = less curvature in the exit pupil.

The Vixen SSWs were a good example--horrendous SAEP in the 14mm, but unnoticeable in the 3.5mm.

Another example: the Meade UWA S4000 eyepieces--14mm had serious SAEP, the 4.7mm had essentially zero as far as the eye noticed.

We're not talking about exit pupils which are dependent on the eyepiece/telescope combo.  We're talking about the entrance pupil which is dependent on the diameter of the human eye's pupil.  Certainly, the limiting factor is the smaller of the two.  That is, even your pupil is fully dilated, a tiny exit exit pupil from the eyepiece determines the size of the system's combined pupil.  Since the human pupil won't contract much smaller than 2mm, an exit pupil of 2mm or less is never going to exhibit SAEP as long as the observer remains centered over the exit pupil.  If the eye drifts off center, there is a chance SAEP could be seen.  Drop down to a 0.5mm exit pupil, and the chances of seeing SAEP would become nil.

I'll bet UK/Euro prices for Chinese sourced eyepieces are significantly less than ours thanks to an extra 25% tariff applied by the US government only to them.  Regular import tariffs on optical gear is maybe 8%, IIRC.  Tele Vue gear is Taiwan or Japan sourced, so it is not affected.

@TheLookingGlass could be seeing subtle SAEP with the smaller entrance pupil.  I believe SAEP becomes harder to detect with larger entrance pupils.  Notice that the smaller the entrance pupil, the more easily mid-field rays will be cutoff.

That's why I measure each independently via photographing the AFOV and TFOV simultaneously with the rulers.

You would need to shorten the tube to accommodate the added optical path length of the Amici prism.  It's probably simpler and cheaper to sell the straight through finder on the classifieds and buy a new or used RACI.

2 hours ago, LDW1 said:

I owned a couple of 100° eps, I was never too keen on them, I have a 31.5mm, 90° Antares widefield which is pretty decent but normally I prefer anything below 80°.

Have you ever written up your experiences with the Antares?  It didn't do too well at f/5.2 in this report on CN.

4 hours ago, Zermelo said:

There is a second hand ES 30mm 82 degree for sale at the moment, I've no experience of them:

 

 

The original mushroom top version is just usable with eyeglasses.  It was also sold as the Celestron Axiom LX 31mm and Meade 5000 UWA 30mm.

The conical top version is the same optically, but has a recessed eye lens making it impossible to use with eyeglasses and a bit more difficult without.

It's not as sharp in the center as a 27mm Panoptic or 30m APM UFF.  Stars remain a bit bloated at best focus in comparison.  Without a reference eyepiece, it might go unnoticed.

It is absolutely flat of field as far as I can tell.  The edge has pronounced chromatic aberration of the exit pupil (CAEP) leading to an orange ring of fire inside the field stop on bright objects like the moon or during daytime use.  I've noticed that planets split into red and blue copies of themselves near the edge slightly separated from each other.

I only keep mine for the immersiveness of the view where I only look on-axis and the edge issues are strictly in peripheral vision.  It's not so good for tracking objects drifting from edge to edge on an undriven alt-az mount for the above reasons.

I noticed that FS=FL relationship, but I couldn't quite put my finger on the reason.  I simply plug my measurements into my spreadsheet that has linear curve fitting derived coefficients from my 70+ measurements.

1 hour ago, TheLookingGlass said:

it would have been cool if they did make a 2" Morpheus, but I think the glass would be huge in order for them to make one, if I am not mistaken?

It might be possible to limit image forming lens growth if a focal reducer first stage as with the 30mm APM UFF were employed in the design.  In the diagram below, the first group acts as a focal reducer while I believe the second group acts as a traditional Smyth lens.  The upper 3 groups are the traditional Panoptic style image forming section where rays are first spread out and then reconverged.

12 hours ago, LDW1 said:

We sold it after 50 yrs last Sept. and miss it every night.

Good timing.  I think you sold it near the peak of the real estate market.  With rising interest rates, a forced march back to the office, and inflation raging, vacation homes aren't moving at all here in the US.

Quick test report on the Aquila (TMB) Planetary II SW 2.5mm:

Measured actual apparent FOV (AFOV): 58° by flashlight method, 57.2° photographically

Measured fieldstop via photography: 2.5mm

Calculated effective AFOV (eAFOV) based on above measurements: 57.5°

Measured usable eye relief: 13mm

Eye lens diameter: 20mm

Measured axial focal length via photography: 2.5mm

Measured radial edge focal length via photography: 2.2mm

Edge magnification distortion: 13.9%

Weight: 162g (5.7oz)

With eyecup folded down and fully screwed down: 92mm long x 45mm wide

Overall, it lives up to its posted specifications very well.

The image appears sharp across the field without noticeable vignetting.

Eye relief is a bit tight for eyeglass wearers, but you can still see a good portion (~90%) of the FOV without pressing in too much.

The field stop is nice and sharp.  However, due to extreme magnification, you can tell the edge is bit ragged due to machining limitations.

I'm really reaching the resolving limit of my 72ED scope.  However, the image held up fairly well.

I've posted an updated 2.5mm to 6mm eyepiece AFOV photo collection including this eyepiece in the following thread:

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.

On 13/10/2022 at 05:26, Stu1smartcookie said:

You do get a bit of mirror shift in the mak . 

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.

On 13/10/2022 at 05:26, Stu1smartcookie said:

Ok so to put my limited knowledge to some use ... the 127 SW Mak apparently has a slightly less that 127 mm aperture ...so in effect the difference may be more than 1" .

The general agreement is that it has about 118mm of clear aperture, or 4.6".

On 13/10/2022 at 08:48, Stu1smartcookie said:

The Mak 127 mm is ok for certain DSO's but has a very narrow field of view (FOV)

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.

36 minutes ago, TheLookingGlass said:

I could never understand why people buy eyepieces and use them knowing they can't take in the entire FOV.

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.

57 minutes ago, Don Pensack said:

The 4th eyepiece in the top row has the worst EOFB I've ever seen in an eyepiece, where 50% of the field is brightened compared to the center.

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.

44 minutes ago, TheLookingGlass said:

The 22mm is the least offender though.

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.