Nikon’s 12x50 SEs were my favourite all-round Astronomy binocular. Let’s see if Swarovski 12x50 ELs improve on the high-standard of the SEs and offer an alternative now the Nikons have been discontinued.

Swarovski EL 12x50 Review

Some years ago, I wrote an open letter to the alpha binocular makers, challenging them to combine the best binocular technology with the optical qualities astronomers take for granted, to deliver a high power, large-objective binocular with the following characteristics:

1)     No visible in-focus chromatic aberration.

2)     A wide apparent field.

3)     A field which is sharp, flat, bright and coma-free to the edge.

4)     Eye relief of at least 16 mm.

5)     Minimal blackouts (spherical aberration of the exit pupil in technical terms).

6)     A focuser as smooth, fast and accurate as Nikon’s HG range.

7)     All the usual features, such as waterproofing, twist-up eyecups, etc.

My frustration derived from the fact that a typical high-end binocular contains more lenses than say a Tele Vue NP-101 telescope with an Ethos eyepiece, that delivers all those things in spades. Yet no high-end roofs of the time met all of these criteria. Really only Nikon’s SE porro-prism binoculars were ticking most of the boxes (though not really the wide field).

Then Swarovski brought out the game-changing SWAROVISIONTM ELs. When I tested them I found that they came closer to my ideal than any other binoculars; but with 42mm lenses that didn’t really help astronomers.

So now that 50mm aperture versions of the SWAROVISIONTM EL are available, an ideal size for hand-held astronomy, the big question is whether here finally is a binocular that meets all my open-letter criteria? Or has Swarovski diluted the original SWAROVISIONTM achievement in scaling it up?


At A Glance



Objective Size


Eye Relief


Actual Field of View


Apparent field of view


Close focus








Data from http://www.swarovskioptik.com

What’s in the Box?



The contents of the big white box: 12x50 ELs, strap, lens covers, case, case strap, cleaning kit, snapshot-adapter.

Design and Build

These 50mm ELs inevitably share a lot in common with their smaller and longer-established 42mm siblings, but some changes have been made and not just larger, more flared barrels.

Swarovski’s 12x50 ELs aren’t that much bigger than the 10x42s.


Having opened that elegant packaging and grasped the binoculars for the first time (still cold from their journey), the first thing that stuck me was how small they are. In fact, for a moment I thought they’d sent me a pair 10x42 ELs by mistake!

Slim and easy to hold: the 12x50 ELs don’t feel like a big binocular in the hand.

The 12x50 ELs do seem very compact and one way in which Swarovski has achieved this is by moving the objectives close to the barrel ends. This has some disadvantages: it makes the objectives easier to damage in the field and could make them more susceptible to stray light – ghosts and reflections.

Swarovski claim use of magnesium alloys in the body and as you would expect the ELs are sealed against water to 4m.


The focuser is fast, taking just over a turn from close focus to infinity. Precision is perfect with no play. The action is smooth but suffers from the occasional ‘stiction’ that afflicts most greaseless focusers.

Dioptre adjustment is effected by pulling the focuser knob to reveal a scale. Turning the focuser now adjusts the dioptre. It’s similar to the old Zeiss Victory FLs’, but lighter yet more positive with a click-stop mechanism. The scale is numbered in half-dioptres too and appears accurate, so if you know your prescription you can just dial in the difference.

Pull the focuser to reveal a click-stop dioptre adjust.

Optics – Prisms

The EL range all employ conventional Schmidt-Pechan roof prisms, complete with SWAROBRIGHTTM dielectric mirror coatings and of course phase coating too. But it’s interesting to note that claimed light transmission is 90%. That’s 5% less than the latest Zeiss HTs and 3% less than Swarovski’s own new SLC 56 models. Why? Because both the Zeiss and SLCs use Abbe- König prisms that employ total internal reflection to bend the light (as do porro-prisms), rather than roof prisms with lossy mirrors.

Optics - Objectives

The ELs are packed with optical technology and have no less than 12 lenses per side (even Leica’s most complex Ultravids have “just” 11), which may explain why they feel heavy for their size (Swarovski’s cut-away view show them fairly packed with glass).

SWAROVISIONTM has four main elements:

·        Special coatings for high transmission and tuned colour rendition.

·        HD Lenses to minimise chromatic aberration.

·        High eye relief so you can see the whole field wearing glasses.

·        A field flattener, so the field of view is sharp to the edge.

Swarovski use their premium SWAROTOPTM coatings on the EL’s lenses and the latest dielectric mirrors on the prisms, but it’s interesting to note that claimed light transmission is 90%. That’s 5% less than the latest Zeiss HTs and 3% less than Swarovski’s own new SLC 56 models. Why? Because both the Zeiss and SLCs use Abbe- König prisms that employ total internal reflection to bend the light (as do porro-prisms), rather than roof prisms with lossy mirrors.

The coatings also include the new SWAROCLEANTM technology that rivals Zeiss’ “Lotutec” to repel water and dirt.

One of the most important components of SWAROVISIONTM is the use of HD lenses to rival Zeiss and Leica. HD lenses contain high-fluoride glasses to reduce chromatic aberration (false colour fringes) the way an apochromatic telescope does. In the ELs, the lenses appear to be a complex four or five element design.

Another cornerstone of SWAROVISIONTM is the field flattener technology that has caused some controversy about “rolling ball” effect when panning. Field flatteners are not new: Nikon’s HGs, Prostars and SEs have had them for decades, as have Fujinon’s FMT line. But the ELs are still among the few “Alpha” birding binos to have them.

There is an article on the web by physicist and optics expert Holger Merlitz that explains in detail why a flat field leads to the rolling ball effect when panning. Here suffice to say that some have found the very flat field of the new ELs makes them nauseous when panning. Astronomers – like me - generally like flat fields, though, because it gives a better view of star fields and big DSOs.

Premium coatings are part of the SWAROVISIONTM concept.


Objectives compared: Leica Ultravid HD 12x50s, Swarovski 12x50 ELs: Leica’s lenses are more deeply recessed, the armour thinner.

Optics - Eyepieces

The eye lenses are very large on the EL50s, just as they are on the 42mm version – about the largest I’ve seen on binoculars. They are about 25mm diameter, deeply concave and remind me of the eye lens on a premium astro’ eyepiece.

Apparent field of view in the 12x50s is slightly larger even than the 42mm ELs’ at 63° (5.7° actual field width). That’s an impressive achievement because in general larger lenses mean longer focal length and hence a smaller field; Swarovski must have tweaked the design to use a shorter focal length objective. That means a risk of higher chromatic aberration, but they’ve avoided it as we will see.

Long eye relief for spectacle wearers (like me) is another part of SWAROVISIONTM. The 12x50 ELs claim 19mm, compared to 20mm for the EL 42s. Eye relief is a bugbear of mine, because you need plenty of it to make binos comfortable to use with glasses. Nikon has always been a favourite manufacturer because they realised the need for good ER long ago, whilst the “Alpha makers” are only just starting to catch up.

In the case of the 12x50 ELs, Swarovski’s claimed 19mm is absolutely spot-on, but only if you measure from the edge of the lens; from the rim of the eye-cup in its lowest set position, eye relief will be more like 16mm, which is how it feels.

Does this matter? It does. You see, my Zeiss 7x42 FLs actually have more eye relief than the EL 12x50s - about 17-18mm measured from the eye cup. But that’s not the way it reads in the sales literature.

I’ve said it before and I’ll say it again here: we need a standard for ER measurement, because at the moment apples are being compared to oranges. If you buy the ELs expecting the kind of super-generous ER of a Nikon SE or HG, you’re going to be disappointed.

Twist-up eye cups are top-quality Swarovski and Swarovski will likely replace them for free.


The 12x50 ELs come with the usual Swarovski accessories: Stay-on rubber objective caps, hinged eyepiece cap, strap, snapshot adapter and case.

The case is different from (better) than the 10x42s’. It is made from stiff cordura, is semi-rigid and has two compartments for accessories, whilst being felt lined to protect the binoculars. At last a case that’s fit for an Alpha bino’!

The snapshot adapter clips around an extended eye cup and then clamps a compact camera lens when you twist it: good in theory, the clamp mechanism’s aperture was too small for my daughter’s camera (a Sony) and too large for my wife’s (a Canon). By the time you read this, Swarovski’s phone adapter may have replaced the snapshot adapter.

Snapshot adapter in place, clipped around an extended eye cup.

In Use – Daytime


The ELs feel good in the hand and the focuser falls naturally under your forefinger. As I said at the start, these seem like quite a compact binocular and they are easy and intuitive to hold and move about, though a touch heavy. The double barrel design pioneered by the old ELs is gradually taking over and it’s not hard to see why.

I am struck by just how snappy perfect focus is: among the very best I have tested. That accurate focuser, combined with wide, deep field, makes watching birds on the wing easy - surprisingly so for a high-powered binocular.  For a greaseless design the focuser is very good and slightly better than my (older) 10x42 Swarovision ELs were: smooth, fast and fluid. Focus from 2m to infinity is one and a half turns.

In my view, dioptre adjustment is the best and easiest ever – delivered by a combination of absolute focus snap with a very precise micro-click-stop mechanism.

I’ve said the real-world eye relief, measured from the rubber eyecup, is more like 16mm than 19mm, but it is indeed sufficient to see the whole field with my glasses on, but only just. The eye cups are the best around though: smooth and easy rotating with a solid feel and 3-positions.

Handling is really easy, belying their high-power. Grip is comfortable and helps control the high-power shakes. For the first time, here is a 12x binocular I would take nature viewing or casual birding, because it’s easy and comfortable to use. I’ve become quite a convert to the double-barrel design and the tapered shape of the 12x50s mean they are more comfortable to hold than either the 10x42 ELs or the 15x56 SLCs.

Unlike so many larger-aperture binoculars, Swarovski have worked hard to make the 50mm ELs compact. Not only do they feel quite small in the hand, they don’t look ludicrous hanging ‘round your neck (unlike the 15x56 SLCs, for example).

The size and weight of the ELs isn’t overwhelming, even for small hands and the tapered shape makes them easy to hold steady.

The 12x50 ELs look quite elegant when carried (unlike some 50mm binoculars I can think of).

The View

Most high-powered binoculars have a disappointing view in full daylight: often a bit dim and narrow, not as sharp and natural and easy as lower-powered models with a bit more chromatic aberration to spoil things. Not the 12x50 ELs.

The view through these is just spectacularly good: like a premium 7x or 8x binocular, but with more reach. For the first time, here is that ‘picture window’ view you get with a Zeiss FL or Nikon HG, but at high power. You only realise it’s a 12x magnification when you take your eyes away and everything recedes into the far distance. The field of view is so wide and flat that you don’t feel constricted the way you often do with high powers. What’s more the 12x50 ELs don’t restrict the view to a shallow focal plane the way some 12x binoculars do: credit the excellent depth of field and quick focuser. Overall, the view is quite simply the best and most comfortable I have experienced in a high-power binocular.

A neutral colour balance, achieved with custom-tuned coatings is a Swarovision boast; it works: colour rendition it completely neutral, apparently identical to the naked eye.

Performance at close range is excellent, so you could use the 12x50 ELs as a long-distance microscope: I really enjoy detailed views of a pair of Blue Tits foraging for berries in the hedge across my garden, with every nuance of plumage picked out. I had fun using them to looking at a painting across my study and pretending I’m in it – close focus works that well.

Overall, the daytime view is a most impressive achievement for such a relatively high magnification.

Flat field?

The much-discussed ‘rolling ball’ effect due to the flat field is noticeable when panning, making the ELs slightly less comfortable than the Zeiss 7x42 FLs, but I certainly don’t find panning uncomfortable, let alone nauseating. Interestingly, careful inspection of the field reveals that it isn’t completely flat: it curves off a little towards the edge so that perfect focus does shift slightly across the field of view. I suspect that this is no accident. With these latest ELs I think Swarovski have listened to their critics and dialled in a touch of field curvature to make panning more comfortable.

However, I also noticed that when using the Zeiss straight after the ELs, their field curvature was really obvious. So, by the standards of other binoculars, the ELs still have a very flat field. If you get perfect focus in the centre, you’ll still ID a bird at the field edge.  For me Swarovski have achieved an excellent compromise between flatness and panning comfort.

Chromatic Aberration

Chromatic aberration is exceptionally well-controlled. What tiny amount remains is mostly from the eyepieces or prisms and increases off axis: focusing through high-contrast objects produces virtually no colour fringing. Overall the level of CA is equal to (or perhaps a touch less) than the Zeiss 7x42 FL – impressive. Watching a Jackdaw wheeling and diving, mobbing a crow against a blue sky is no problem and tree branches silhouetted against a clear dusk sky show a wonderful crispness. In the morning, I can watch a flock of pigeons roosting on high branches, lit by the low sun, with their plumage absolutely clear and defined.

These HD lenses make a real difference because objects silhouetted against the sky no longer have their contrast and detail ruined by false colour.

In Use - Dusk

Dusk performance is simply excellent: I can see into the copse opposite my house, even when the tree-shaded darkness there is blackly opaque to the naked eye. There is a modest degree of  ‘white out’ – light from the sky reflecting in the optics - when using the ELs in deep dusk with a bright clear sky, but it is restricted to the lower part of the field and isn’t a problem.

The large lenses, fine coatings and wide field all contribute to a very considerable ‘image intensifier’ effect at twilight. Even with your pupils dilated to use the whole exit pupil of the binoculars, the ELs remain sharp with snappy focusing.

Thankfully, the ELs do not suffer from blackouts/kidney-beaning (spherical aberration of the exit pupil). Moving your eyes about has no effect on the view, another bonus for comfort and ease of use. This is especially noticeable at dusk or at night, when it’s not so easy to tell if your eyes are perfectly placed. The Nikon SEs often left me puzzled looking at a black night sky devoid of stars … until I realised I’d just hit an eyepiece blackout spot.

In Use – The Night Sky

Testing the 12x50 ELs on a frosty November night.

I consider 12x50 to be an ideal size for general astronomy, so I’ll give a detailed account of the EL’s performance on the night sky. Skip the detail if it doesn’t interest you.

The Moon

The 12x50 ELs show the Moon just as it is with nothing added or taken away – a cold solid ball of luminous whites and greys. Contrast is excellent and resolution very high. On a gibbous Moon, it’s easy to pick out strange Reiner Gamma in Oceanus Procellarum, the Rupes Altai and Cyrillus embedded in the terminator. The ELs show real Lunar detail and your own shakes are the limiting factor.

Roughly how you might see the Moon through the EL 12x50s: still small at this magnification, but crisp and contrasty and full of detail.

I notice how crisp the focus is and how much faster and more precise it feels, even than my Zeiss 7x42 FLs.

Make no mistake, the view of the Moon with the ELs is about the best I have seen with binoculars – very much the ‘two small APO refractors’ ideal that so very few binoculars achieve.

However there is the first hint of a problem. The bright Moon in field produces no ghosting or reflections, but while viewing Jupiter a few degrees away, there is a sudden bright ghost of Moonlight reflected in the optics. I can reproduce this problem at will with a streetlamp.

Overall I notice that at night, working around the Moon or bright lights, the 12x50 ELs produce a few more reflections and ghosts than the class leaders in this area. My guess is that to keep length down they have moved the objectives close to the barrel ends and paid a price in stray light resistance as the result.


In a twilit sky Venus showed a tiny, brilliant crescent that was absolutely crisp like it is through my Swarovski 15x56 binoculars, but without the chromatic aberration. In near darkness, Venus’ brightness did overwhelm the prisms to produce just a little flare, but even so the phase could still be seen and this is typical of even the best prismatic optics, my 15x56 Swaros included.


Like Venus, Jupiter shows up as a perfect disk with no stray light or flare and its Galilean moons are clearly visible, even when close to the planet. But (unlike the 15x56s), these didn’t show a hint of the equatorial belts.

Deep Sky

On an evening in late November with dark, transparent skies I was able to find a whole host of DSOs quickly and easily with the ELs. A Messier Marathon would be fun with these. Stars become mildly comatic after ~80% of the field width, but this is barely noticeable and the impression is of a wide, sharp flat field full of pin-point stars.

The field is wide enough to fit in the whole Hyades or (just) both Orion’s belt and sword.

Globular clusters M92 and M13 in Hercules were easy to find and satisfyingly bright, as were M15 and M2; only smaller, fainter M69 near Lyra was a tougher challenge.

In terms of galaxies, M31 showed its bright core and extended nebulosity, the fainter companion and the dark lane cut-off; the relatively high magnification and wide field seem to suit it particularly well. M33 was bright and easy to find too. Bodes Nebula (M81 and M82) looked very good through the ELs, with M81 clearly extended and fuzzy, M82 denser, more compact and linear.

Finding the Dumbbell Nebula in Vulpecula was a bit harder than with the 15x56 SLCs, as was the Ring Nebula (M57), but I could clearly pick both out from the starry background after a search.

Open clusters look really good through the ELs due to the flat field and pin-point stars. Both the Pleiades and the double cluster looked as good as I have seen them with hand-helds. Sweeping the Milky Way is satisfying with the ELs and stellar colours are vivid due to the pin-point stars those sharp optics yield.

Clusters M36 and M38 in Auriga were clearly resolved into masses of stars and showed their characteristic shapes. The EL 12x50s seem to sit at a nexus of aperture and magnification, combined with superb optics, that works well for clusters and extended DSOs. The double cluster with its arc of stars stretching north towards more clusters in Cassiopeia, was especially beautiful – better than in most other binoculars, again due to that combination of field, aperture and power.

Comet Lovejoy was easy to find and quite spectacular in the morning sky before dawn, even in strong Moonlight, with a clear tail, extended nebulosity and bright nucleus. With all the fuss about Ison, people have neglected this bright comet that can be seen high in a dark sky.

In general, the 12x50 ELs compared well with the 15x56 SLCs for astronomy. The smaller, lighter ELs are much easier to hold and use and give better views of extended objects and star fields, but they don’t give quite such a good view of smaller DSOs or of planets, just due to the lower magnification and smaller objectives. Aperture and magnification win on small DSOs. But whereas the 15x56 are a specialist observation binocular, the 12x50 ELs work well for everything else as well.

Overall, I rate the 12x50 ELs top of the pile as a general purpose hand-held astronomy binocular.

The Swarovision EL 12x50 vs Nikon SE 12x50

Up to now the Nikon 12x50s have been my favourite high-power binoculars; not any more.

The Nikon 12x50 SE is my current reference standard for hand-held astronomy binoculars. When I tested the Leica Ultravid HD 12x50 a few years back I found it wasn’t really better than the Nikons overall, despite being heavier and (much) more expensive. So how do these new Swarovski 12x50s fare against the Nikons?

A summary of the differences between these two fine binoculars:

·        The Nikons are 10% lighter at 900g, compared with 998g for the ELs.

·        The new ELs actually have a several mm less eye relief than the Nikons, but less blackouts to compensate. I would prefer the Swarovski compromise: just enough ER, but with excellent twist action cups and no blackouts, in comparison to the generous ER, fold-down cups and sensitivity to eye position of the Nikon SEs.

·        The ELs have a significantly wider field at 5.7°vs 5° for the 12x50 SEs: an impressive achievement, given the flat field and good eye relief. This helps make them a more general-purpose binocular.

·        The ELs’ field is even flatter than the Nikons’.

·        The ELs have a slightly cooler colour balance that is even noticeable if you project the exit pupil onto white paper.

·        The ELs have slightly less chromatic aberration.

·        Both show a bit more ghosting and reflections than the class leaders, but the Nikons show some minor ghosting with a bright Moon in field, whereas the ELs do not.

·        Depth of field is very similar in both.

·        The ELs focus closer.

·        The ELs are fully waterproof, the Nikons are not.

·        The Swarovskis cost about three times as much as the Nikons.


The 12x50 ELs are not perfect, but they come close. Almost everything about them is class-leading and my only small gripe would be that their stray-light performance at night, whilst good, is not the best.

In every other way, these are a superb binocular and sufficiently better than my previous reference standard to make them a worthwhile upgrade if you can afford them.

For me perhaps the best thing about the 12x50 ELs is that they don’t feel like a high-power binocular at all. The view is so wide and bright and deep that they do everything well, an unusual virtue in a 12x binocular. Take them birding or nature viewing during the day; hunt for owls or deer in the woods at dusk; check-up on that brilliant star you’ve been glimpsing through the branches (you confirm it’s Venus by checking the phase); then use them for spotting Messier objects after dark, followed by a quick survey of the terminator’s highlights when the Moon rises. Given the price of premium binoculars, it makes a lot of sense to have a single pair that works for everything.

However, if you can manage the weight, bulk and high magnification, tight eye relief and daytime CA, the 15x56s SLCs do perform at a higher level for astronomy, especially if you enjoy hunting down smaller DSOs.

Finally, the 12x50 ELs tick most of the boxes as far as my ‘open letter’ criteria are concerned:

ü Virtually no chromatic aberration.

ü A wide apparent field (63°, not the 70° I asked for, but we’re getting there!)

ü Super-sharp, flare-free optics, flat to the edge.

ü Real-world eye relief of about 16mm.

ü A smooth, fast focuser.

ü All the usual features like twist-up eye cups and full waterproofing.

The Swarovision 12x50 ELs are very highly recommended. They are the best high-power binoculars I have tested to date and the only high-power binocular I would happily use day-to-day because the view is so wide and bright and they are so easy to handle. The question of whether they are worth 3x the price of Nikon’s 12x50 SEs, which are perhaps 85% as good, is less relevant now the Nikons have been discontinued.