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Best 25mm eyepieces ever!

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#1 Astrojensen

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Posted 11 May 2012 - 03:03 PM

...or at least the best ones I've seen.

Last Saturday, I attended ATT in Essen, Germany. It's the largest astro-gear show in mainland Europe and the largest in the world, together with Astrofest in London and NEAF in the US. I am not sure which one is the largest, actually.

Anyway, at ATT there's a lot of people selling secondhand scopes, eyepieces and other things. Lots of odd bits and stuff as well as truly high-end gear at very reasonable prices. I lucked out and happened to come across a pair of 25mm Zeiss West (Oberkochen) microscope eyepieces converted to 1.25" format. At 110 Euros apiece, they were not exactly cheap, but I knew what I was looking at. Still, 220 Euro is a fair bit of cash for me, so I decided to think about it for a little while.

And you know how that usually turns out, don't you?

I couldn't get them out of my mind. After getting a bit to eat, I returned to the table, where I had seen them. And...

They were still there! And not only that, the price had been reduced to 99 Euro apiece! I realized this was probably the opportunity of a lifetime, so I forked over the cash and grabbed the precious eyepieces.

Needless to say, I speculated endlessly for the next several days about their possible performance and what I should do, if they were somehow not so good as I hoped they would be, based on what I had read here and elsewhere about the near-magical performance of Zeiss research-class microscope eyepieces.

My worries were totally unfounded, of course.

The first views of the Sun with my 150mm f/8 achromat, stopped to 120mm, using Baader Solar Film and using a Baader Maxbright binoviewer and Baader T2 prism showed an extremely good view, despite thin, hazy clouds. The sharpness was incredible, as was contrast. There was simply no glare, ghosting or reflections. Nothing. It was like looking out a window. An open window, I might add. It was that good. My memories of using UO 25mm VT orthos and TS Kellners crumbled under the awesome views. It is really hard to describe, but it was as if there was simply no glass in the eyepiece and the eyepiece itself almost disappeared in a way I've never experienced before. The AFOV is probably around 45° or so, but it feels substantially larger, because of the extreme comfort. The view was incredibly good and I was very unhappy to see the Sun slowly disappear in clouds.

Now you might think that there is no way to top such a superb view, but you're wrong. A few days later, I did just that: I took out my 85mm f/19 Zeiss apochromat.

Using an INTES Heschel wedge and B+W Optik polarizing and ND 3 filters on the Baader Maxbright, I had a heart-stoppingly good view of the Sun. And the scariest thing is that I know it can get even better, because even on this occasion, the sky was not entirely free from thin clouds. And yet the view was insanely good. These eyepieces may be the first ones I've ever seen that truly do the 85mm Zeiss justice. Contrast and resolution, as well as comfort and lack of glare and other annoyances was simply on an otherworldly level I've never experienced before. An f/19 is easy on eyepieces, but on the other hand the lens is so perfect, that it takes an extremely good eyepiece to truly show everything it's capable of. To what extent this was true, I had not realized until that moment.

I have yet to test them under conditions that can fairly be called even "very good" and they've already taken the place as the undisputed number ones in my small collection of 25mm eyepieces. I curse the fact that I'll have to wait almost three months to test them under dark skies on deep-sky objects, where their extreme resolution and contrast will really shine, such as globular clusters. Not to mention faint galaxies. And the Moon through the refractors! Oh, sweetness! A couple of high-end barlows and I think I can retire a fairly large chunk of my planetary eyepiece collection.

Many people have raved about Zeiss (as well as Nikon and Olympus) microscope eyepieces before, but I must admit I was just a little bit sceptical. How could they possibly be *that* good? Well, they are, and now I am raving myself!

I fear this might be the first stage of a very expensive addiction.


Clear skies!
Thomas, Denmark

#2 langejcarl

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Posted 12 May 2012 - 07:54 AM

You could make a quick profit and sell them to me for $100 Euros each!

Thanks for sharing your experience and letting your words clearly express your excitement.

#3 Erik Bakker

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Posted 12 May 2012 - 03:14 PM

Thomas,

Congrats on these great Zeiss eyepieces. Are yours 25 or 27mm?

I have a pair of 27mm Zeiss eyepieces, they are incredible.

#4 Astrojensen

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Posted 13 May 2012 - 02:10 AM

Hi Erik

They're 25mm's, adopted from 10x microscope eyepieces. Stunning performance. I now try to find a barlow or combinations of barlows to give me planetary magnifications. I am afraid that I'll have to look at Zeiss barlows or Baader FFC's, perhaps Tele Vue Powermates, to get something good enough to match the performance of these incredible eyepieces. As I said, it's the start of a very expensive addiction.


Clear skies!
Thomas, Denmark

#5 johnnyha

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Posted 13 May 2012 - 12:04 PM

Awesome. Whats the serial # Thomas? Is it these 4-element diopter eyepieces, #444232-9904?

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#6 Astrojensen

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Posted 13 May 2012 - 03:01 PM

Hi Johnny

No, it's not those and I can't find a serial # on them! They're not shown on the APM second hand page either. They're marked 10x/22 B (B for brillenträger, eyeglass user). I took a few pictures today, I'll try to find the time to upload them soon.

I did some more testing today under a VERY clear sky, though in quite unsteady seeing. Contrast and sharpness is phenomenal. They have instantly replaced three eyepiece pairs, namely my 28mm orthos, 25mm UO VT orthos and 25mm TS Kellners. AFOV is around 50° - 52°, visibly bigger than the UO orthos and more comfortable eye ergonomics to boot. Compared to the quite comfortable TS Kellners, it's like a layer of grease has been wiped from the view! I was actually happy with the TS Kellners, but the Zeiss'es is in a whole other league.

They also barlow extremely well, until the scope f/ratio gets too long, somewhere over f/60. At f/68 (85mm f/19 Zeiss + 3.6x barlow) every dust mote inside the binoviewer was shown as a gray blob in the field of view. Interestingly enough, dust on the eyepieces didn't show up all that prominent.

The view with the Baader 1.7x GPC in 2x mode in front of the T2 prism on my 150mm f/8 achromat gave a most superb view, far superior to my 12.5mm UO VT's. On the 150mm f/8 (stopped to 120mm f/10), I could also use the 3.6x barlow for around 173x with excellent results, though the seeing was not good enough to handle the high power. I suspect that on the 120mm f/10 I could use at least a 5x barlow combination for high-power lunar-planetary observing.


Clear skies!
Thomas, Denmark

#7 etsleds

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Posted 13 May 2012 - 07:12 PM

Thomas, congrats on the new Zeiss peepers! I enjoyed my set from APM for quite a while, although long-term I struggled enough with proper eye-positioning & blackout that I sold them last year. Is your model reasonably easy to maintain proper position?

Regards, Andrew.

#8 PJ Anway

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Posted 13 May 2012 - 07:17 PM

Thomas,

Very nice report and congratulations on the Zeiss eyepiece find! I've been using Zeiss aspheric orthos for solar viewing for several years now and they yield a very fine image, with excellent contrast. I purchased them through APM, but they are in the Zeiss microscope housings. Here is a pic:

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#9 PJ Anway

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Posted 13 May 2012 - 07:22 PM

Here is a closeup: (I added the larger rubber eye-cups in the previous pic.)

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#10 PJ Anway

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Posted 13 May 2012 - 07:37 PM

They're marked 10x/22 B (B for brillenträger, eyeglass user).

Thomas, Denmark


Thomas,

I thought Zeiss later replaced the "B" mark with the "eyeglass" icon, seen on both Johnny's eyepiece and mine. So Johnny's and yours may be the same eyepiece, his just being a later production run. I know there is definitely plenty of eye-relief on mine for eyeglass wearers.

#11 Astrojensen

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Posted 14 May 2012 - 04:45 AM

Hi Andrew and PJ

The eye ergonomics on mine are the finest I've ever seen. No issues at all. No blackouts, difficulty finding exact eye distance from eyepiece, etc.

They also look completely different from anything I've seen here and on APM. I may have got my hands on some rarities! Now you're on the edge of the seat and I'm not even at home, so I can't upload a picture, since I don't have the USB cable for my camera with me. Maybe my parent's PC has a port for the camera memory card. I'll find out.

I had them out today for half an hour under reasonably good seeing, using the 150mm f/8 stopped to 120mm f/10. With the 1.7x GPC in 2x mode I was enjoying perhaps the finest white-light medium power image I've ever seen of the Sun. Just absolutely incredible. The complete absence of any glare or reflections in these eyepieces makes the visual experience absolutely amazing. It's like you're not even using a telescope, but a spaceship. I can't wait to try them on the Moon! Saturn was quite stunning last night at 96x and even 173x was not bad, despite the low altitude and bad seeing. My 2x barlow is not good enough, though, and must go. I need something of quite a different caliber now!

Nice setup, PJ, BTW.


Clear skies!
Thomas, Denmark

#12 Scott99

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Posted 14 May 2012 - 07:59 PM

Thomas - wow, what a lucky find! I have one of this 25mm Zeiss also. these are no longer made in Germany these days and they usually go for $250 on Amart. Yours sounds like an older version, APM sold these for years with their custom barrels.

I am one of the people that rave about this eyepiece! It's only 3 elements, the edge correction is excellent out to about 44-45 degrees. I actually consider it to be superior to the 25mm Zeiss Abbe ortho! Yes, blasphemy I know, but it's got one less lens element. As you discovered, the contrast is superb, the stars appear as extremely small specks. I could see right away that the coatings were easily as dark as the ones on the ZAO orthos and AP SPL's I owned when I got this eyepiece. Some of the darkest coatings I've ever seen.

It ate my 25mm Clave and 24mm Tak LE for breakfast! I liked it so much I bought the 16mm version, which adds a barlow element for 5 total lenses.

Finding a pair makes an even better deal.

#13 Scott99

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Posted 14 May 2012 - 08:09 PM

Thomas,

Very nice report and congratulations on the Zeiss eyepiece find! I've been using Zeiss aspheric orthos for solar viewing for several years now and they yield a very fine image, with excellent contrast. I purchased them through APM, but they are in the Zeiss microscope housings. Here is a pic:


PJ - interesing - I actually preferred the OEM 44 degree field stop, so I sold the APM one I had and ordered one directly from Zeiss.

My favorite eyepieces are the AP SPL's, which go from 4mm-12mm, for me the 25mm Zeiss serves as the perfect extension of the set. 3 elements, FOV is nearly the same, same edge sharpess, same incredible contrast, dark coatings, etc. here it is w/ the 16mm:

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#14 langejcarl

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Posted 19 May 2012 - 07:39 AM

Are there some buying tips when looking for Zeiss eyepieces? What markings to look for and which ones to avoid?

I see a lot out there such as:

20x OPMI 20x focusable

E-PL 10x/20

PL 10x/20

Kpl W 10x/20

PK 20x

K 20x

#15 Astrojensen

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Posted 19 May 2012 - 02:09 PM

I'd definitely try to find the modern types and steer clear of the older ones, unless I was a collector, of course. The newer types have superb coatings and moderately wide fields. They're also extremely well corrected.

The "10x" is equivalent to 25mm focal length. They usually have apparent fields of view between 40° and 55°. The number behind the "10x" is the field stop diameter in millimeters. Mine are marked 10x/22, so they have a field stop diameter of 22mm. AFOV is about 50°. Another useful thing to look for is a symbol showing a pair of glasses or the letter B, which means "brillen" or "brillenträger", glasses or eyeglass user, in German. K could mean "Kellner" or "Kompensation", I am not sure which, perhaps both, depending on the eyepiece. In the latter case, it is a special eyepiece made to correct for spherochromatism in apochromatic microscope objectives (I think!).

A good way to make sure you get something useful, is to keep an eye out for eyepieces made for stereo microscopes (not normal microscopes with a binoviewer). Stereo microscopes often have larger fields of view and use eyepieces with 30mm barrels, but this is also becoming a standard on modern microscopes. They also don't use apochromatic objectives and generally not phase contrast either, so you have a much greater chance of getting normal eyepieces and not something odd that was meant to be used with special equipment. Be particularly cautious about Zeiss eyepieces with an infinity symbol on them! These are made for Zeiss'es special microscopes with collimated light beams, where the tube length has been made irrelevant for the magnification by adding collimator lenses after the objective and recollimating lenses just in front of the eyepiece or IN the eyepiece, hence my warning. These may be completely unusable on anything else than a Zeiss microscope with infinity optics. MAY be, I am not 100& sure.


Clear skies!
Thomas, Denmark

#16 langejcarl

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Posted 20 May 2012 - 06:38 AM

Would these be good performers? Since there is no obvious serial number are they probably an older model? Would it be more ideal to look for ones with a 25mm field stop?

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#17 Stellarfire

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Posted 20 May 2012 - 08:13 AM

I already played with the idea to use these 3-element eyepieces for binoviewed planetary observations in my 6" f/7.33 APO refractor, along with Baader's FFC or the A-P BARCON.

I checked on CN some older threads on the 3-element Zeiss microscope eyepieces and their use in astronomical telescopes. All reviewers reported that these 3-element microscope eyepieces are indeed very sharp on-axis, but complained a quite noticeable pin-cushion distortion at the very edge. What is your observation on this matter?

Stephan

#18 Scott99

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Posted 20 May 2012 - 10:56 AM

I already played with the idea to use these 3-element eyepieces for binoviewed planetary observations in my 6" f/7.33 APO refractor, along with Baader's FFC or the A-P BARCON.

I checked on CN some older threads on the 3-element Zeiss microscope eyepieces and their use in astronomical telescopes. All reviewers reported that these 3-element microscope eyepieces are indeed very sharp on-axis, but complained a quite noticeable pin-cushion distortion at the very edge. What is your observation on this matter?

Stephan


Stephan - In my f/7.5 refractor the 25mm's are almost completely sharp out to about 44 degrees. After than you get some bloat in the star images. I preferred the view at 44 degrees over 54, but I think APM found that most people preferred it at 54 degrees. With the OEM 44 degree field stop, the edge correction is similar to the 25mm ZAO eyepieces, or maybe even better.

those older "west germany" ones look great to me! After a cleaning I would expect them to be close to the newer ones, they look multi-coated.

#19 Astrojensen

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Posted 26 May 2012 - 04:06 AM

UPDATE. First planetary views.

OMG! :bigshock:

The Moon is... Almost impossibly sharp in these babies. In fact, they're so sharp, you'll have to be extremely careful when focusing, as the SLIGHTEST hint of being out of focus instantly reveal itself as a noticeable drop in detail. Not that there still aren't many details visible, but the amount explodes once you hit critical focus. It's like *BAM* and the lunar surface comes alive. I found it easiest to creep up to the best focus with the 1:10 reducer on the crayford, then microfocus with the diopters on the Maxbright. It took an insanely small amount of a turn to hit absolutely best focus. Other eyepieces I own are nowhere near as sensitive, but also don't give anywhere near this insane level of detail. At 48x (no GPC) and 62x (1.25x GPC in front of diagonal, 1.3x, 150/1200mm SW achro, stopped to 125mm), the lunar surface was resolved WAY down below the resolution of my eye. And the contrast. Oh my. I observed the Moon until it slipped behind some neighborhood trees low in the west.

Mars was in an unstable part of the sky, but despite being only 8" at the moment, clearly showed its phase, a polar cap, which was very easy to see, and a few vague, greenish markings. The seeing was quite unstable, though, so I didn't spend much time on it. I was at 170x, using my 2x barlow lens, cell only, attached to the 1.25x nosepiece of the Maxbright, where it gives 3.55x.

I turned to Saturn instead. Bigger and brighter and a little higher in the south.

:bigshock: :jawdrop: :woohoo:

For some odd reason, the seeing in this part of the sky was vastly better than over in Mars' part of it. And Saturn was SPECTACULAR! For many years, I've had not so good impressions of my old asian barlow (probably an early GSO), but the view of Saturn was heart-stoppingly good. At 170x, the most fantastically sharp Saturn I've seen in many years, and undoubtedly the finest this telescope has ever showed, came slowly gliding into the field. It was just perfect. It was beyond words. I think I observed Saturn for about 1.5 hours, until it slipped behind my tall hedge to the southwest. The seeing slowly deteriorated, but even as Saturn began to slip behind the branches, it was still firmly very good. The Cassini division was like an etching, never wavering out of vision, only fuzzing a little on occasion. The equatorial band was definitely double. The crepe ring was faintly glowing in the ansae and clearly visible where it crossed the planet. Limb darkening was obvious, though subtle. The ring shadow on the planet and the planet shadow on the ring added to the 3D-feeling. Not since observing Saturn in 1995 with my friend Darnell's 178mm Meade ED and binoviewer have I had a finer view of Saturn.

After Saturn had set, I turned to deep-sky, now using full aperture of the 150mm f/8 achro. I am at 55°N, so the twilight nights have already begun, so there was not going to be any really faint things visible. The SQM said 20.50. I turned to M13, which was easily visible in the 8x50 finder. The stars in the 25mm Zeiss'es are just fantastically sharp. Extremely tiny points, sharp almost to the edge in the f/8 and tight even there. Even at 48x, the big globular showed lots of faint stars in long chains, curving away from its glowing, fuzzy core. Now the long eye relief of the 25mm's came in as a disadvantage. I couldn't cup my eyes closely enough around them to block stray light well enough. I changed to my 20mm GSO Superviews. The field was a bit darker and more stars where showing up and I could block stray light much better, but the view was not nearly as sparkling as before, despite all my attempts to focus just as carefully as with the Zeiss'es. Eye comfort with the 20mm GSO's is very good, but there was just not the depth and the snap to the view as with the Zeiss'es. I added the 1.3x GPC and went back to the Zeiss'es. The globular showed crisper and much more numerous stars, for sure. I changed to the 1.7x GPC, mounted in front of the prism, for 1.65x. The view was extremely good. A shame it wasn't darker.

I was getting very tired now, so I looked at bit at Vega at 170x, to test the image quality, mostly because of the barlow. It was extremely sharp. Glow around the bright star was exceptionally well controlled. Hmm. No need to be in a rush to find a better barlow, it seems. Or will the view only be even better then? Guess I need one after all!

Impressions: These eyepieces seem near impossible to beat. They also have a few quirks, but those can be overcome, I think. The worst is that their barrels are slightly undersized, so that they wobble ever so slightly in the Maxbright eyepiece holders. This is bad, because it can lead to merging issues. The solution so far has been not to tighten the setscrews, so that both eyepieces will always lean in the same direction, due to gravity. The downside of that solution is quite obvious...! No security, should the binoviewer accidentally rotate downwards, and we all know how easy that can happen. The generous eye relief also generates issues with stray light, as noted above.

Another quirk is their generous eye relief and very relaxed eye position. These are clear advantages when it comes to comfort, but you may also not notice that your eye is not exactly centered on the exit pupil, so that image quality can suffer, until you notice that the softening of the view is not due to seeing issues!

A definite advantage of their build-in diopter adjustment is that you can focus the field stop! This creates a very curious effect, in that the "spaceship effect" of these eyepieces are much stronger when the field stops are sharp. Oddly, it also makes the field appear larger! It has the effect of making the field stop appear at infinity, thereby making it seem as if you're looking at the stars through a VERY large window from a great distance. It creates an illusion of vastness that is not subtle in the mind. The "window effect" is very strong. Other eyepieces make it seem as if you're looking through a surgical microscope as a small cell or amoeba, even when you're looking at a galaxy. Such eyepieces have just that "eyepiece effect". You can't shake the feeling, that you're looking through an eyepiece, while the Zeiss'es makes the scope disappear, letting you look out a window into space. The only eyepieces in my arsenal that show a similar strong effect (and I think that is mostly due to their much larger AFOV) are the GSO Superviews.

Bottom line: Using these Zeiss microscope eyepieces are turning out to be a very special experience. The best part is that I've yet to see so much through them. The journey has just begun.


Clear skies!
Thomas, Denmark

#20 johnnyha

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Posted 26 May 2012 - 07:58 AM

Awesome report! I hav one question because these eyepieces have been repeatedly referred to in this thread as having three elements. So if yours have diopters... are you sure it's only 3 elements? The eyepieces I linked to earlier have diopters for instance, and they have four elements in three groups.

#21 Astrojensen

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Posted 26 May 2012 - 08:09 AM

So if yours have diopters... are you sure it's only 3 elements?



I don't know how many elements they have. Have I said something about that? I can't remember! :o That's not to say that I haven't! :crazy:

All I know is that they perform as if there wasn't anything in there at all, except a magical window into space itself.


Clear skies!
Thomas, Denmark

#22 johnnyha

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Posted 26 May 2012 - 08:16 AM

You haven't actually said "3 elements" but Scott99 and Stephan refer to 3 elements. I know there is a 3 element version but I would imagine it doesn't have a diopter.

#23 Scott99

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Posted 26 May 2012 - 08:56 AM

You haven't actually said "3 elements" but Scott99 and Stephan refer to 3 elements. I know there is a 3 element version but I would imagine it doesn't have a diopter.


I thought the APM ones were the same optics regardless of whether they focus or not, but there's no way to confirm it for these old ones. Some of them might be a different design.

Nice report Thomas! sounds like some good planetary seeing. Mars is getting so small and close to the horizon it's just about over this time I'm afraid.


#24 Erik Bakker

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Posted 26 May 2012 - 01:51 PM

So if yours have diopters... are you sure it's only 3 elements?



I don't know how many elements they have. Have I said something about that? I can't remember! :o That's not to say that I haven't! :crazy:

All I know is that they perform as if there wasn't anything in there at all, except a magical window into space itself.

Clear skies!
Thomas, Denmark


:lalalala:

This discussion desperately needs some pictures :rules:

#25 Astrojensen

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Posted 26 May 2012 - 02:07 PM

I thought the APM ones were the same optics regardless of whether they focus or not, but there's no way to confirm it for these old ones. Some of them might be a different design.



There are definitely different designs. I don't know the number of elements in mine, but I do think they *might* be a four-element, three-group 1-2-1 König variant, kept to 50° AFOV. This would explain the very good correction and the huge eye lens. I can't say for sure, since the lenses are so phenomenally well polished and coated that I can't see them inside the housing (!!!) when looking from the field stop side, but I can try to count the visible recesses inside the housing, where there might be a lens... I seem to be able to count three such recesses. The field stop is 22mm wide, while the eye lens is 30mm wide!

I honestly can't see the glass. It's an unreal feeling. There's a row of tiny and faint reflection, seemingly floating in mid air, otherwise there's nothing the eye can see. Truly remarkable.


Clear skies!
Thomas, Denmark






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