Review: Zeiss T* 22/10x (and Sharp Eyepiece Shootout!)

[Stratis]

As I've been posting lately, I have accomplished the near-impossible in landing a matched pair of an extraordinarily rare and little-known eyepiece.

Zeiss, a company with a long and storied history of optical excellence, count large surgical microscopes as part of their catalogue. For many years they shipped a floor-standing dissection microscope with a complete binocular headpiece that was itself a fully capable binocular telescope.

With an objective up-front, a conventional (as opposed to standard microscopy) eyepiece formula is required.

Enter the Zeiss T* 10 x / 22 B.

The Hype

This family of eyepieces is defined not by a swanky series brand or a known design like 'Plossl' (in fact, I have no idea whatsoever what design these follow...), but simply by the numbers and letters on the barrel;

• T* - 'Transparent'; this denotes eyepieces given the Zeiss full multi-coating treatment
• 10 x - The magnification of the eyepiece, against a 250mm focal length objective
• 22 - The diameter of the field stop in mm
• B - 'Binocular'; not sure about this one, I think it means longer eye relief for binoviewing

All this calculates out to a roughly 25mm eyepiece in astronomical terms, with an AFoV around 50-55deg, slightly narrower than a Plossl but nothing like a Vixen LV at 45deg. The eyepieces come in matched pairs, so it is important to keep them together if they came off the same microscope; obviously this can't always be managed, but in this case I am assured they came from the same original unit. 

The body of the eyepiece is chunky and feels extremely solid, there is no rattle whatsoever, except from the threaded ring that would be used to attach it to the microscope. The eyecups are of the softer 'indoor' scientific type, and it is possible to extend the lenses upward out of the body. This has been described on other sites as an 'extendable eye cup'; this is not the case. The entire optical train of the eyepiece is shifted, essentially the 'eyepiece' moves as a threaded cylinder inside the housing. Therefore it is a dioptre adjustment, for focusing each eyepiece independently. For this, the movement is very strong and holds focus like a vise.

In future, I will add a pair of 1.25mm barrels to this, for tonight (the only clear night I've had for a long while ) I simply held it in a recess in a 2" dielectric diagonal adapter, which was sound enough for a few minutes of testing.

Now these units have been the source of some... interesting words, on other forums. 

They have been described as 'impossibly sharp', that 'the telescope just disappears', 'stars are painfully bright points' and so on. After seeing a pair on AB&S for hundreds of pounds I knew I had to have some... although not at that price

I do not wish to get in trouble by quoting The Other Forum too much, but these words should suffice;

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.

...and that is mild compared to the gushing praise that both this and other authors have heaped upon this family of Zeiss 'surgical-grade' eyepieces. Now I was deeply suspicious upon reading this, as I have had many experiences with eyepieces described as 'razor sharp' or 'bright, contrasty views' on the internet but failed comparison tests in person. I am an extremely harsh judge of eyepieces and scopes in general, and only really post reviews of those for which I have absolutely nothing bad to say. I have plenty of bad to say about the Ethos, for example. The only line of eyepieces I can't really complain about have been the Pentax XW series, which blow my mind for sharpness and flare suppression, and are the standard by which I judge all others.

The scope chosen was the WO GT-81 triplet, which delivers zero CA to my eyes and is extremely sharp, with a rock-solid focuser.

The Shootout!

Tonight I was fighting with thick, fast-moving cloud that gave a few minutes of super-transparent sky and then orange sky-sludge for the same... frustrating, and I resolved to get the tests done quickly rather than go for a wide selection of objects. I'll offer a basic impression and a score for each eyepiece in the test; I am not going into huge depth as some reviewers do inventing metric scales and so forth, but the results will be internally self-consistent. Obviously I'm using an 80mm scope here, so no deep sky objects are chosen as they would be too small at these focal lengths to really judge. 

The targets of choice:

• Vega - I use Vega (sometimes Rigel) to judge the smallest 'star shape' an optical system can produce.
• Albireo  - A test of colour reproduction, sharpness and contrast at lower scales. It's not a challenging double but it still shows up a bad eyepiece well
• The Milky Way - A less scientific test, I just point the scope at a random patch of the milky way. This helps determine the optical efficiency and limiting magnitude.
• The (nearly) full moon - Ultimate test of flare suppression, CA introduction and contrast under tough conditions

The Contenders

The eyepieces chosen to compete with the Zeiss:

• Takahashi LE 18mm - My go-to general-magnification EP, sharp and bright with zero ghosts and a very predictable focus behaviour. Gets the job done.
• Tal Gen-II Plossl 30mm - A semi-legendary and rare piece, these show field curvature at the edges but are the sharpest Plossls I've ever found by a great margin and have wonderful colour reproduction
• Celestron Classic Silvertop Plossl 25mm - My newest addition, and a contender with the Tal for best Plossl; not as sharp but less curved at the edges
• Baader Classic Ortho 18mm - I bought this for splitting doubles with a TV Powermate, it shows the least 'flare' of all the eyepieces but a narrow field

These choices represent the best I have in the same rough focal range. Technically I have a Meade Research Grade Ortho at 10.5mm which is super-sharp but too different in every other way to make a fair comparison, and 'widefield' EPs like the TV Ethos 8mm and Pentax XWs; these are not a good match either, as they simply present the view differently. I suspect I will come to have a favourite presentation between the Zeiss and the Pentax (as I have with the Pentax and the Ethos) but it's hard to make fair like-for-like comparison.

So, the results;

Takahashi:

This eyepiece is very familiar to me and did not disappoint. Vega was a 'normal sized' sparkling diamond with a slightly cool blue tone, no ghosts but a hint of flare. Albireo was reproduced with a clean high-contrast split, although the colours were actually a bit muted. This came as a surprise as I haven't tried this particular EP with this particular object before; I suspect the Tak has an inherent cool tone which was equalising the two partners more than it should really. The Milky Way showed dozens of tiny points; averted vision showed dozens more. The full moon came through nicely; rills and craters were well-defined at the terminator, but the flare issue did return somewhat.

Tal:

I love this eyepiece; since I first loaded it up I knew it was special, even as its many downsides frustrate the hell out of me. Vega was notably sharper and better-focused than the Tak, a diamond yes but no longer 'sparkling', no ghosting or reflections. Albireo sprang out with superb contrast and confirmed the lack of colour in the Tak; none was in evidence here, with a golden/aqua textbook pairing. The Milky Way didn't reveal much with averted vision however, and I noted the field curvature was totally eliminating some faint stars nearer the field edges, I feel absolute light transmission may be slighter lower in this eyepiece. The moon showed some flaring, in-line with the Tak's performance, although the terminator showed a fraction less sharpness and contrast. This is interesting given the superior performance on star-like objects.

Celestron:

A surprisingly poor performer in this lofty contest, given how well I regarded it previously and the fact it stomps on all of my non-premium EPs with ease. I suspect this is simply proof that coating technology has improved in the 20-30yrs since this eyepiece was stamped out. Vega did not focus as well, with a slightly enlarged Airy disc and some flarepoints surrounding it. Albireo was faithfully reproduced with decent colour reproduction, but the gap between the partners was less well-defined as in the others, something not accounted for by reduced power. The Milky Way again showed fewer stars than the Tak, the same number as the Tal Plossl really... perhaps it's a Plossl thing. The moon to my great surprise showed actual CA around the rim; this can only be from the eyepiece as no others caused this to appear, and a very large amount of flaring. I still like this eyepiece as a top-end Plossl, but this is a very tough contest.

Baader:

I always find this eyepiece vaguely boring... almost like a piece of furniture or an honest but uninspiring politician. It does it's job, not well enough to remember but not badly enough to remark upon. Vega showed a similar view to the Tal, with a sharp, bright point free from flare or 'sparkle'. Albireo came through with typical ortho excellence, very sharp with deep contrast between the two, the colour was reproduced but in a flatter, less engaging way somehow. The Milky Way was a strong showing, with many, many tiny stars well-defined and averted vision revealing many more. Transmission was better in the Ortho. The moon also was a good showing with the lowest flare so far (nearly none) and sharp contrast on the terminator.

I can best sum up these scores thus;

The Champ

I tried both of the Zeiss eyepieces with the same diagonal and scope as the others; identical performance was seen on both, they truly are matched in every way. Before I go on, let me just say that I do not have "New Toy Euphoria" or some kind of sunken-cost blindness you see on a lot of reviews where someone has spent a lot of money and is swayed towards the positive. I paid a stupidly low amount for these from a surplus store that clearly didn't know what they had, after about a five minute off-the-cuff search, not expecting to find any. I was totally prepared to sling these on AB&S for a huge markup if they weren't better than what I already had.

So.... do they deserve the praise heaped upon them elsewhere? Are these Zeiss surgical eyepieces actually that far ahead of the already excellent field of premium eyepieces astronomers have to choose from? Are they really 'heartstopping'?

In a word.

...yep.

I confess to feeling some measure of disbelief when looking through the Zeiss at Vega. The first signs began as I found focus; the star resolved to a point as good as any other eyepiece in the test, with the double-double clearly visible nearby. As I went to test for astigmatism by rocking in and out of focus, something happened that has never happened with any eyepiece I've ever used.

I hadn't actually achieved focus, not really. 

Even out of focus, this EP was a match for a Baader Classic Ortho... as I racked further out carefully, I was able to hone in on an image of Vega that I spent at least five minutes staring at just to comprehend. The star was utterly tiny, finally I understood the meaning of 'diffraction limited'... it is hard to estimate such small scales, but I would estimate an illuminated area around half that of the BCO. It was truly profound, the light from the star was brightly coloured blue and almost too sharp to look at. Finding true focus was a challenge to my visual acuity, the point of absolute clarity took a number of attempts to find but once found and locked in....

All I could say was "Oh.... wow...."

I swung across to Albireo and was treated to the finest view of this pair in my memory. The division between the stars was utterly crisp, a word I now associate with this eyepiece; bright, hard points with a gulf of actual deep velvet black between. The stars were even tinier than Vega due to the lesser magnitude, but still shone through with the full intensity of their colours. I spent several happy minutes just gazing at a double I've spent hours on already. Even at this modest power, the stars were as cleanly resolved from one another as with any eyepiece I can remember... I suspect the Zeiss will barlow very well.

With the sky worsening I quickly dragged myself away from the star to a random spot of the Milky Way and was again blown away, this time by transmission, which easily equalled the Ortho but with a sharper, crisper view. The stars retained the same miniscule proportions down to the limits of vision, which I suspect would be close to the theoretical limit of the scope. It was at this point it struck me that another writer had been absolutely correct; it really is like looking out of an open window. There are no distortions, no aberrations, no geometric inconsistencies in the view whatsoever which would remind your brain you are viewing a telescopic image. The stars were simply.... there. In a way an Ethos cannot deliver to me, as I am always aware that this view is artificial... with the Zeiss I was able to forget this fact, indeed, the eyepiece seemed to make the telescope just disappear. Spectacular.

The Moon was the last target and a rewarding one. No flare, anywhere, with the exception of the atmospheric skyglow from the moon itself. The terminator was hard and dark, again equalling the Ortho on test but, that word again, more crisp somehow. Zero CA was evident in the image, and as I looked around I noticed something I had not been able to see in any other other eyepieces... the star near the moon's position. About three 'moon widths' away was a medium-low brightness yellow star which had been hidden by glare in all other eyepieces on test. The Zeiss had controlled flare so well that this star was now clearly visible alongside the moon. Now I am not a great fan of lunar observation, I know many are, but I could see myself spending many hours with the moon and a binoviewer just admiring the clarity of the features, the depth of shadow and the sharp highlights of crater walls... even at medium power these features reached out of the field to me, in an almost three-dimensional manner. 

I now cannot wait to try them with my 8" SCT, and see if I can put that transmission to work on DSO hunting

All in all, these are easily the most technically pure oculars I can imagine, certainly that I have used. The view is simply what your telescope delivers, unadulterated. The price of this is a relatively narrow field of view, a mere 50degrees or so, although 100% of this field is usable unlike the Plossls on test which lost substantial sharpness further out. 

I mentally compared this to my favourite, the Pentax XW14, and had to conclude that the Zeiss had higher contrast and sharper detail, although the Pentax is very, very close and delivers it in a much wider field. That said, picking up an equal to one of the finest ocular series ever produced for £60 cannot be sniffed at

From now on, this will be my planetary and small-DSO eyepiece; I can think of no other I'd rather use. I shall keep the wider-field oculars in my case for more immersive, more enveloping experiences of space; but for sheer perfection and freedom from shifting distortions, the Zeiss take the crown.

If you can find some of these, I strongly advise you go for it. If you have a nice, sharp scope to put them in I doubt very much you will be disappointed.

[Roy Challen]

Great report Stratis, and I'm not at all surprised by your findings.

It's actually possible that these are Huygens type eyepieces- the various microscopes I use at work (including Zeiss) use them. Additionally, by far the sharpest eyepiece I have is my 25mm Zeiss Huygens (cheapest eyepiece I have! ), splits the double double with ridiculous ease. And scatter? What scatter?

Yes, Zeiss - the best.

[michael.h.f.wilkinson]

Very interesting. I have on occasion been tempted by these. Might go for one if I get a chance.

[michael.h.f.wilkinson]

BTW, the description sounds a bit like my experience when I switched from a Yashica 2.8/135 telephoto to a Carl Zeiss Sonnar T* 2.8/135, or when I got the Carl Zeiss S-Planar T* 4.0/100 for my bellows. They are just breathtakingly good. There's some real wizardry going on at Carl Zeiss

[niallk]

Great review - wow!

[Piero]

Very interesting review! 

I understand your feelings when you said "it really is like looking out of an open window". I had the same impression when I saw neurons and senescent cells through a microscope that cost more than 150k. Just purity. 

[estwing]

interesting read...thanks for sharing

[laudropb]

Very interesting and full report. Your findings do not surprise me having worked with various Zeiss microscopes over the years.

[John]

Fascinating report and an interesting read. Thanks for pulling it together

[alan potts]

A very interesting report indeed and nicely put together. I have often fancied trying something like these but there is a greater chance of Concorde landing in my garden and even if I came across a pair here it is likely the owner would want the GDP of a small country for them.

[Stratis]

Thank you for the kind words

I confess I was somewhat hesitant to post my findings after just looking through the Zeiss in isolation.... I felt like I must be biased somehow, or it's actually no better than my other 1.25" pieces but I haven't used them in a while so I've forgotten... I didn't think they could possibly be as good as they seemed.

That's when I decided to do the shootout, for my own peace of mind as much as everyone else's

They really did stomp the competition... whatever Zeiss did here, they've created a near-perfect median-AFoV ocular, I cannot imagine an improvement on this besides just... more AFoV at the same level of sharpness, which is probably a mathematical impossibility.

I'm still sort of in shock at the focal sharpness and Airy disc size, in two years I have always assumed the star size was a function primarily of the telescope, not the eyepiece. I still can't really believe it, even though I've since tested them on terrestrial targets and found the exact same result, much superior sharpness and contrast. 

The only eyepiece I have that approaches (but falls short of) this level of sharpness is a 37mm 2" ex-NATO Konig that was pulled off a battle tank gunsight and converted; that includes some un-named heavy metal glasses which are probably against an EU regulation by now, but that one does come close to the Zeiss; same sort of good (but not inflated) field, great colour reproduction and total absence of aberrations.

They are rare obviously, but there is a guy on AB&S selling a pair with a Baader Mk V binoviewer, he's willing to split the items I think.

[michael.h.f.wilkinson]

Airy disk size is primarily a function of the aperture of the scope, but what you see at the EP is convolved by whatever residual aberrations the EP introduces. At low magnification, the image of the airy disk of the objective is very small, probably below the limit of resolution of the eye, so aberrations from the EP may in fact dominate. At very high magnification, the size of the Airy disk may be dominated by the aperture

[jetstream]

Nice review I might have to try one of these if ever available. If the out of focus Zeiss beats a BCO it must be very good.

[Stratis]

Nice review I might have to try one of these if ever available. If the out of focus Zeiss beats a BCO it must be very good.

There has been some scuttlebutt that the Zeiss lens groups used in the construction of these 25mm micro eyepiece is actually the same (or similar as makes no difference) as the TMB 25mm Aspheric Orthos, simply in a different housing and field stop. A guy who owned both says they are exactly the same visually.

If that is true, and the Zeiss lenses are the TMB Asph Ortho lenses (or rather, TMB use the Zeiss), they are one of the sharpest eyepieces ever offered to the general public. That would certainly fall in line with the user descriptions of the TMB Aspherics, which are held as truly legendary examples of the optician's art. The defeat of the BCO, itself a fine lens but still built to a cost (The BGOs and Meade RGOs are both superior to the Classics), is less surprising if you think of the Zeiss as a TMB.

Amazingly it's easier and cheaper to source the Zeiss versions than the TMB Aspherics these days

[jetstream]

I own 4 Zeiss products and they are all very good,the one I want they don't make anymore- the ZAOII... how does this micro eyepiece compare to those? any word floating around out there?

[Stratis]

I own 4 Zeiss products and they are all very good,the one I want they don't make anymore- the ZAOII... how does this micro eyepiece compare to those? any word floating around out there?

Well I can echo the words of Dr Michael Lalk, a reasonably well-known German astronomer, who performed a detailed at-the-eyepiece comparison of several Abbe Ortho families including the Baader Genuine Ortho, which were from the outset designed to be a widely-available but optically-equivalent version of the ZAO-II series. He had this to say;

"My result: Baader -Planetarium has succeeded with the Genuine Orthos.  They represent a worthy execution of the orthoscopic eyepiece, in my opinion, and make it possible for those who do not possess the Zeiss Abbes to own an equal alternative at a fraction of the price.  No exotic glasses are used here, surely, as Zeiss.  But, my observations show that it is actually not possible to differentiate, in use, between a Zeiss "Abbe", a Pentax SMC-Ortho, or a Baader Genuine Ortho"

So from a performance perspective, it seems that a BGO or SMC-Ortho will do you, although they perhaps lack the collectable element of the ZAO-IIs. The BGOs are available if you look about, and are a notable step up on the BCO series which is basically a cheaper, more mass-reproducible version. 

I would be very interested to see these Zeiss 25mms in a direct comparison with a BGO... sadly the BCO and Meade Research Grade Ortho are the only ones I own. The RGOs are considered essentially equivalent to the BGOs in that once you have the Abbe design down to micrometer perfection with modern multicoatings there really is very little to 'improve', but I only have the 10.5mm which isn't a fair comparison.

[YKSE]

Very nice review, I'm looking forward to read more of your observing reports.

There's a long interesing thread on CN about great Zeiss microscope eyepieces.

[jetstream]

I look forward to further reports down the road on Jupiter and some faint DSO, this may be a very good Horse Head eyepiece and should show the entire thin thread of the Veil easily.

[Stratis]

DSO and Barlow Update!

With the planets just out of reach recently whenever the sky has been clear, I took tonight as a chance to get in a few quick DSOs, and to see how well the Zeiss responds to barlowing.

In addition, I have just received my 1.25" barrels, internally blackened and machined by eBay seller Micro_Crystal; this guy has quite a lot of good microscopy stuff. These are well-made, with filter threads and a striated barrel surface to reduce friction when mounting.

Finally, I found on eBay another Zeiss eyepiece, this one somewhat different; this little guy is labelled 'PI 10x/18 B', so I expect good eye relief, technically a longer focal length than the 25mm (if it has the same 10x mag but a smaller 18mm field stop, it must be a longer FL), and whatever 'PI' is meant to mean This EP is much smaller and lighter, has a curved lens surface vs. the planar 10x/22s, clearly of at least a slightly different optical formula. 

Inside this eyepiece (the lens elements just fall right out if you foolishly unscrew the barrel...) are two cemented elements, paired with a single-element eye lens, which to me says it's likely to be a very fine Koenig design (although I thought Koenigs had planoconvex field lenses?) rather than anything more exotic.

Testing

Another irritating windy night but at least some clarity between the fast-moving cloud banks. 

I figured I'd do a quick test on the DSOs within reach, then switch back to double-splitting but this time with some extra kit in play. I have a pair of 1.25" Astro-Engineering barlow lenses, which both contain ED glass and have proven well superior to any other barlow I've used with the exception of TeleVue Powermates. 

On this particular night I chose the AC710 'Supreme' 2x barlow, and the AC519 'ImageMate' 4x. Neither have ever shown a hint of false colour or distortion, I personally rate them up there with TeleVues in terms of optical quality at a much more sensible pricepoint, and I say this as a guy with two Powermates in the bag

The scope today is my new Explore Scientific 80mm triplet, which has yet to receive a proper run-out thanks to the weather. This matches nicely the previous instrument in the first test, also an 80mm triplet. On the side, I am quietly figuring out which one of these two little beauties to actually keep

Please note, the DSO images herein are not eyepiece projection photographs, they are just there for a bit of flavour.

DSOs

I popped the 10x /22 into the scope and started a hunt for some easy DSOs for the 80mm on a manual Alt-Az... this took a little longer than I'd have liked without a finderscope (anyone know how to attach a standard finder shoe to an Explore Scientific scope?) but I guess I must be learning my way around as I managed to track down a good number. For each I spent at least five minutes with the bigger Zeiss, then swapped out for the baby one as a comparison.

On the Andromeda Galaxy, I was impressed straight away and remembered my previous comments... the view was utterly crystal sharp, I was able to use even the dim stars surrounding the object as focus references, when many eyepieces make that a vague and difficult experience. Focus attained, I could clearly make out the traces of the dust lanes draped around the bright, bluish core and even (with effort) trace outwards to the extremities of the spiral arms. This view exceeds any of my other eyepieces in clarity; I found myself wishing for a big, fast Dobsonian to really give this eyepiece the light grasp it needs to make the best of itself. 

Swapping to the 'Baby Zeiss', I was gratified to see a really very similar view, albeit at a smaller scale. The dust lanes were still visible, but I felt they were a little less distinct; the outer reaches of the galaxy were harder to visually pin down. I noticed, very strangely, a notably different colour cast between the two eyepieces; the bigger Zeiss were more neutral white, while the smaller gave a slightly cooler, bluer impression.  Overall a nice little eyepiece, but much closer to an 'average' orthoscopic with a much narrower field and a slight contrast loss against its big brother.

On to a much lesser-known open cluster, M29, the 'Cooling Tower'. The view was beautiful... all members fit within the field of view, and shone out as tiny, bright points. Again, I have seen this cluster before but found it unremarkable, this eyepiece rendered it really quite enchanting. 

In the little Zeiss, the blue cast repeated; star shapes were kept under superb control just as in the larger eyepiece, but the narrower rendition did rob the view of a little spectacle. I also noticed something for the first time; the baby Zeiss was much less accommodating of eye position. The big Zeiss showed no kidney-beaning and a nice big sphere of space to park your eye in without any degradation, but the little one demanded laser-focus, perhaps betraying its more humble microscopic origins.

I managed to get a quick view of the Cygnus Veil before a huge cloudbank closed off that section of the sky. The contrast advantage of the Zeiss was clear and unmistakable on this faint gossamer object, I was able to locate some filamentary features with a broadband view. I added my favoured nebula filter to the optical train, the 2" DGM Optics VHT freshly imported, and was rewarded with a clear perception of around 70% of the arc. As observers of the Veil will note, seeing it at all in an 80mm scope is not always easy, and the Zeiss didn't waste a single photon. If anything, the restricted AFoV made it easier to see dimmer objects, as the light is concentrated into a smaller surface area and not spread out (my chief complaint of the Ethos line) too much to register. I would still prefer the view through my 8" SCT for sheer light grasp, but the 80mm did really well here, and I could recognise (if not really explore) what I was looking at. Sadly I could not try the smaller Zeiss on this target.

The final target was another little cluster I quite like (and one of the only targets available with that cloud bank smothering Cygnus), M35 in Gemini. It's tough to find and rewarding to be able to do so manually, although I did have to resort to a 2" 38mm SWA to do my sky-scanning  . Once found and back under the Zeiss, it was tiny and pretty and perfect as a little postage stamp constellation. The various stellar spectra were strong and gorgeously contrasted. The baby Zeiss again did alright, very sharp and correct, although the cooler tone seemed to rob the members of the same colour contrast I now knew existed.

Overall, this is a spectacular DSO eyepiece; contrast is clearly its greatest asset, it really does feel like every single photon is being captured and brought to you, no scattering, no flare, no drama. You really do miss the wider immersion that a 2" can grant you, but in giving that up you gain so much in terms of sharpness and contrast I can think of no better companion for those really tough Caldwell objects. I really, really want to try this eyepiece in a bigger scope, if anyone in the Oxford area has a huge, fast Newtonian and can predict the future weather, I would love to hear from you 

Barlow Response

In my initial review I speculated that a barlow lens would really synergise well with the Zeiss, given the Airy disk plunging below the limits of my visual acuity. If the barlow is particularly finely made and does not compromise the view in any way, the Zeiss should simply keep offering tiny star shapes with ever-darkening and widening gulfs between.

I tried first the double-double of Lyra Epsilon, but at 480mm of focal length they remained as stubborn points. Upping to 2x helped not a bit, even 4x (for a magnification of 77x) started to show some elongation and dark shading between, but couldn't quite separate the pairs. I guess the 120x recommendation for this pairing is accurate, I have little trouble viewing the partners in my Cassegraine scopes. I suspect a nice long-focus refractor like the Lyra Optics or Tal 4" would work very nicely with the Zeiss on double-splitting, but I'd find it hard to beat a fine Mak at this particular challenge. The smaller Zeiss did no better, and actually failed to control star size as well as I went to 4x. This does make me think that  the 10x/22s are a superior optic.

What I did note was that the stellar shapes actually got smaller and more compact-seeming as I upped the magnification; I suspect this is an artifact of the dimming of the view. At 4x in particular, the star images were really quite refined and delicate indeed, reinforcing my determination to try the Zeiss in my 150mm Rumak which gives the most refractor-like view of any scope I own besides an actual frac.

Next I tried familiar Albireo as I had a strong basis for comparison owing to the first test. I was rewarded at native power with another glorious view, partners cleanly separated and vibrant in their respective spectra. Barlowing up simply blew the partners apart, opening a deep black chasm between the two. The star shapes were simply divine. Being mid-magnitude to begin with, the images shrunk to a delicate filigree, with colours still perfectly reproduced but restrained to a tiny little speck. Unlike my earlier Plossls and so on, the stars did not bloat out to a spherical-looking orb when heavily barlowed up; they retained a fine, almost spiky appearance, simply at diminished intensity. Perfect. The baby Zeiss replicated this performance albeit with less authentic colours; the cool cast really screws up Albireo, particularly coming from the dead-on neutral of the 22s. The slightly larger star shapes were also in evidence.

After that I simply went binary-hunting, swinging around the sky with the barlow mounted so as to increase chances of spotting a separation. I found a number I doubt I'd ever seen before, mostly very dim, and the Zeiss just ate them up; every barlow was used and was useful, I longed to try my 5x Powermate but the clouds were getting worse. I particularly enjoyed the many, many spectra revealed as I roamed the Milky Way; even at a fast pan, I was able to distinguish between stellar types with relative ease. The smaller Zeiss showed up slightly less effective transmission, very dim stars seemed slightly more difficult to pick out. 

Bonus Round - the Moon again!

I noted as I went to pack up that a low-hanging cloud front had cleared for a while, revealing the crescent moon; I swung around for it immediately. The same three-dimensional feel returned, the crater walls were just so crisp.... in fact the seeing was causing me more difficulties than anything, and thanks to the fidelity I could really see the seeing. I popped in the 4x barlow and was rewarded with a very accommodating view, no loss of sharpness and enough clearly visible lunar features to keep me busy for hours, had the clouds not started to roll back in. The range of shades and the tiny hints of craterlets and ejecta was beautiful, and honestly bested my experience with the Pentax XW series on this target.

The baby Zeiss was decent, again rendering a bluish-white moon rather than the yellow-neutral in the 22; it then occurred to me that despite having spent a lot of time bashing this little EP against the legend of its bigger brother, it was actually a damn fine long-focal length ortho-a-like. The view surrendered little to the 22, and I would have been equally happy with either had the AFoV been constant. As it was, reduced image scale was a little harder to deal with, making the moon feel 'far away' down a tunnel rather than reflected in a perfect mirror. 

Conclusion

All in all, a resounding success for the Zeiss and a very rewarding classical night of observing; no widefields, no fancy electronics, not even a star map to guide me. Just the sky, my memory, and a little 80mm refractor on a Vixen Mini Porta. The beauty in the Zeiss made this experience really a little bit special, it took away that feeling of directionless frustration and slight malaise that can haunt you when viewing the sky in a small scope with a subpar eyepiece; it is this feeling of not-quite-disappointment that I feel robs a lot of beginners of their future in astronomy. The Zeiss brought a little bit of magic back to this very ordinary experience.

If I hadn't seen such riches I could live with being poor; I know now I will be unable to ever return to my Plossls, except perhaps very fine examples. My 1.25" selection will simply be Pentax XW on the low end, scaling up to Zeiss on the mid range and I guess a 30mm Takahashi LE for scanning. With a good little barlow I can cover all the ranges I will ever need, and this gives me the chance to really simplify my eyepiece case: XW7, XW20, Zeiss 25mm, Tak 30mm. Four eyepieces, all with something special to offer and no looking back for me. I also know I can cease my ortho hunt, as ultimate sharpness in an ergonomic optical package is now within easy reach.

The Zeiss really is a superb general-purpose eyepiece, from double-star to DSO and lunar viewing. I suspect it would be a stunning partner for planetary work. Perhaps the focal length is a little long for really hardcore double-splitting, but if you are serious about that discipline you almost certainly have a long refractor or Maksutov and can bear a 25mm for the sake of comfort, which the Zeiss also delivers in spades with no kidney-beaning or blackouts unless you get really, really far off.

The little guy there on the left, I have been quite tough on tonight, but to be honest is still a superior EP to many in my collection and cost very little on an eBay auction. It feels more like a long ortho than the 'Plossl crossed with an ortho' feel of the 22, but plenty of people have cases full of orthos and this would make a fine cast member in that performance.

Both pieces delivered superior, sublime sharpness and what has to be best-in-class contrast. Control of optical aberration was absolute, the fields were flat as a pancake, sharp all the way to the edge and free of glare, flare, ghosting... you name it. In each performance category save flare control, the 18 lagged behind the 22. I suspect they are simply built to different price points and tolerances, but if the 18 was all I had I'd still love it.

I'll be keeping these forever and probably passing them on to the next generation, they are artifact-grade and I love them to bits 

Paul

[John]

Thats a very interesting and enthusiastic report Paul

Are these Zeiss eyepieces available to purchase anywhere or is it just a matter of "getting lucky" and coming across them somewhere ?

[Stratis]

Thats a very interesting and enthusiastic report Paul 

Aye well it's very easy to be enthusiastic about these! I remember being impressed by the scientific sharpness in the Meade RGO and Baader Classics, but wishing they would give a more pleasing, 'cinematic' view. These wide, flat and sharp EPs grant that wish and then some, I almost wish I could provide them to a few more people and compare impressions etc so I know it's not just my opinion. There are astronomers out there with a much broader experience of top-shelf eyepieces than me!

Are these Zeiss eyepieces available to purchase anywhere or is it just a matter of "getting lucky" and coming across them somewhere ?

Sadly seems to be a matter of sheer luck of the draw.

Following this review I know one other SGL member managed to track down a pair in Germany, and there was a bloke selling a pair on AB&S for a rather steep price. If you see some of these with the wider field stops (above 20), I'd advise buying them if the price isn't too eye-watering. With the barrel conversion these have run me £70 each, which isn't bad at all; I suspect I'd pay up to twice that, going any further would make me a bit nervous but then the TMB Aspherics sell for considerably more than that.

The 'little' Zeiss in this review tends to be a lot more obtainable, I've seen two go by on eBay. The 18mm field stop is actually just a bit of plastic, the lenses themselves are much larger, so I am going to try to modify this one to increase its field diameter. If I succeed, it might be a more accessible route to this sort of sharpness, as the view even in the cheaper one was really quite lovely, just restricted to an annoyingly narrow field, around 45deg or so.

That seems to be the party piece of the 10x/22s... flat, sharp but also Plossl-like AFoV.

[John]

So more or less unobtainable for the majority of us ?

We will have to enjoy them vicarously though your reports then Paul   

[Roy Challen]

Finally, I found on eBay another Zeiss eyepiece, this one somewhat different; this little guy is labelled 'PI 10x/18 B', so I expect good eye relief, technically a longer focal length than the 25mm (if it has the same 10x mag but a smaller 18mm field stop, it must be a longer FL), and whatever 'PI' is meant to mean This EP is much smaller and lighter, has a curved lens surface vs. the planar 10x/22s, clearly of at least a slightly different optical formula. 

I tried first the double-double of Lyra Epsilon, but at 480mm of focal length they remained as stubborn points. Upping to 2x helped not a bit, even 4x (for a magnification of 77x) started to show some elongation and dark shading between, but couldn't quite separate the pairs. I guess the 120x recommendation for this pairing is accurate, I have little trouble viewing the partners in my Cassegraine scopes. I suspect a nice long-focus refractor like the Lyra Optics or Tal 4" would work very nicely with the Zeiss on double-splitting, but I'd find it hard to beat a fine Mak at this particular challenge. The smaller Zeiss did no better, and actually failed to control star size as well as I went to 4x. This does make me think that  the 10x/22s are a superior optic.

Paul

Thanks for the update Paul, it's interesting to read your experiences with microscope EPs. There's a few long threads over on CN by some very knowledgeable people, and their reports mirror yours very closely.

I'm fairly sure the 'Pl' stands for planar - ie 'flat field'. Other microscope EPs are labelled EPl or WPl - extra flat or wide flat- I think.

I'm quite surprised though, that you didn't manage the double double split even with only 480mm f/l and x77.

John, these eyepieces aren't too difficult to obtain - they occasionally come up on ABS or Astromart, but are fairly common on ebay. The problem with ebay is fakes and/or severe overpricing. Seems like the Zeiss name is a license to charge whatever people like. Also APM in Germany sells a few varieties - none cheap!

[Stratis]

So more or less unobtainable for the majority of us ?

We will have to enjoy them vicarously though your reports then Paul 

 Yeah well same can be said for those lucky so-and-sos with that wooden-cased BGO set, or the TMB SuperMonos, or Pentax XW30/40s

I'm quite surprised though, that you didn't manage the double double split even with only 480mm f/l and x77.

Me too, and to be honest I need to go back and check that. I am not immune to being an idiot and looking at the wrong thing, and I only had ~30secs at a time to make an observation before having to switch. If I've been staring at something totally different but nearby I shall not be amused...

John, these eyepieces aren't too difficult to obtain - they occasionally come up on ABS or Astromart, but are fairly common on ebay. The problem with ebay is fakes and/or severe overpricing. Seems like the Zeiss name is a license to charge whatever people like. Also APM in Germany sells a few varieties - none cheap!

Just so; they are obtainable, it just takes a bit of persistence and luck. If you want to shell out, APM would probably track some down for you. 

[John]

How do they handle reasonably fast newtonian optics ?

I'd expect the centre field still to be nice but what happens in the outer 50% of the field ?