Swarovski 10x56 SLC HD Review

Swarovski’s quietly revamped 56mm SLCs are in fact a complete and quite radical re-design that includes HD optics, high-transmission Abbe-König prisms and a much more compact body. The old SLCs were one of my favourite binoculars; are these even better?

Last year when I reviewed the Zeiss 10x54 HTs I said that I’d be willing to try living with just a single pair of full-size binoculars for casual birding, nature viewing and astronomy. Sadly, the Zeiss 10x54s didn’t quite do it for me, mainly because the of the typical Zeiss off-axis coma/astigmatism and field curvature which doesn’t matter so much in the daytime, but really spoils a binocular for astronomy.

For many years Swarovski’s big-eye 15x56 SLC Neu were my favourite astronomy binoculars, but they were too high power, too dim in the daytime and had too little eye relief for general-purpose use. And that’s without the false colour, which was too much for my picky tastes.

Then, a couple of years ago, Swarovski quietly updated their 56mm SLCs. I say quietly, because they made almost no fuss about them at all. You’d think this was just a cosmetic revamp then. In fact the new 56mm SLCs are one of the most radical new models Swarovski has released in recent years, in some ways more so than their fabulous ELs. Why? Read on.

At A Glance

Magnification	10x
Objective Size	56mm
Eye Relief	19.5mm
Actual Field of View	6.3 degrees
Apparent field of view	60 degrees
Close focus	3.9m
Transmissivity	93%
Length	192mm
Weight	1195g

Data from Swarovski

What’s in the Box?

The contents of the big white box: 10x56 SLCs, strap, lens covers, case, lens cloth.

Design and Build

The older SLCs were a fairly conventional large roof prism design with a triplet objective using ‘normal’ (i.e. non-HD) glass. The new model has several major technological improvements and design changes to fix the shortcomings of the old model that I’d noted in my test of the old-style 15x56 SLCs:

· HD lenses to curb chromatic aberration (false colour fringing): the old SLCs had too much.

· Abbe-König prisms (like Zeiss FLs and Dialyts) to improve light throughput and brightness: the old model was a bit dim in the daytime.

· Longer eye relief to allow a full-field view with spectacles: the old SLCs were short on eye relief for specs wearers like me.

· A significantly shorter, slimmer design: the old ones were very long and bulky.

If you think all this makes them sound like serious competition for Swarovski’s more expensive 10x50 EL model, you would be right. Which is why, I suspect, they’ve played the new SLCs down a bit.

Body and Ergonomics

The 10x56 SLCs are significantly shorter than the previous model and slimmer too. They are a compact pair of binoculars for their aperture, but still quite heavy at nearly 1200g, perhaps because they still use aluminium not magnesium for the body. They have two-stage sculpted thumb cut-outs on the back to make them easy to hold.

Appearance of the 56mm SLCs is now aligned with the 42mm SLC models, with two-texture armour that is warm, comfortable and grippy but doesn’t attract dust and marks like the Zeiss HTs I tested.

Build quality is typical Swarovski – flawless and excellent, identical to the more expensive ELs. Styling is plainer than the Zeiss 10x54 HTs, but quality is actually slightly better (the Zeiss had minor paint and armour flaws that these SLCs do not).

Swarovski’s new SLCs have double cutouts for extra comfort.

Focuser

The focuser is much the same as the newer EL models and different from the previous SLC’s. It’s both smooth and fast, taking just a turn from close focus to infinity. The click-stop dioptre mechanism is accessed by pulling the focusing knob which reveals a scale; it’s an ideal mechanism – easy to adjust and impossible to knock out of alignment in the field.

New SLCs have a dioptre adjustment like the ELs – pull the focuser knob.

Optics -Prisms

I mentioned the major optical improvements in the new 10x56 SLCs above. Now let’s look at them in a bit more detail.

Zeiss have long used a special type of prism that is neither a Porro nor a Schmidt-Pechan, but something called an Abbe-König - strictly another type of roof prism. The good thing about this type of prism is that the light is bent around by total internal reflection (just like porros), with no mirror coatings required (unlike conventional roofs). This means the 10x56 SLCs, like the Zeiss FLs and Dialyts, simply transmit more light than even the best conventional roofs. Swarovski quote 93% light transmission: that’s 3% more than the Swarovski ELs and so the view is a little brighter in the daytime. Interestingly, Swarovski don’t advertise this feature at all; I only know about it from reading a technical post on their blog and by noting it omits their ‘Swarobright’ mirror coatings (because it doesn’t have mirrors!)

Note: the 42mm SLC models use conventional roof prisms.

Optics - Objectives

The new 56mm SLCs also have the high-fluoride (‘HD’) glass in the optics that most premium binos employ these days and that the smaller SLC models have had for a few years. This is a good thing because it’s supposed to minimise chromatic aberration (false colour fringing) on high-contrast parts of the view. However, not all HD binoculars do this as effectively as others.

The lens coatings are among the very best and incorporate ‘Swaroclean’ technology to shed dirt and finger marks. Interestingly they are different from other Swarovski coatings I’ve seen in recent years, being slightly pinkish in hue as opposed to greenish. I think this higher transmission in blue-green makes for a more vivid view. The coatings are significantly less reflective (i.e. better) even than my Zeiss Victory FL’s.

To achieve the optical excellence of these new SLCs, Swarovski have packed them with glass: 12 elements per barrel, according to the spec sheet. Behind the objectives lie several knife-edge baffles to eliminate stray light.

Swarovski’s 56mm HD objectives.

Barrel internals are ridged and baffled.

HD lenses: Swarovski 10x56 SLC vs Zeiss 7x42 Victory FL. The SLCs’ coatings are less reflective.

Optics - Eyepieces

These have complex eyepieces (i.e. not simple Kelners or Plössls) with big 25mm eye lenses.

Apparent field width is a fairly generous 60 degrees, but that’s not quite as much as the Swarovski 10x50 ELs or the Zeiss 10x54 HTs (though the latter’s usable field width is arguably less due to more off-axis field curvature and even some residual coma/astigmatism).

Eye relief is a very generous 20mm or so, just as Swarovski claim. This is slightly more than the EL 12x50s I tested and makes them usable even with chunky specs that sit a long way off your face. Huge eye relief often comes with a downside: blackouts as you move your eye around (the Nikon SE range suffer from this defect). Technically it’s called spherical aberration of the exit pupil, but you don’t need to know that because these 10x56 SLCs simply don’t suffer from it!

All that eye relief does mean you need lots of adjustment in the eye-cups and these have it, with four positions and enough travel to accommodate just about anyone.

The exit pupils look properly round and un-vignetted; internal reflections are well suppressed.

Eye-cups have three extended positions, lots of travel, to accommodate the long eye-relief.

Accessories

The 10x56 SLCs come with all the usual accessories: case, strap and caps.

The padded case is the same as the EL models’ and a big improvement on the case for the old SLCs (it’s also a bit better than the Zeiss 10x54 HTs’ case too).

The strap is the usual Swarovski item, ditto the band-on objective caps and adjustable eyepiece cap. I had trouble getting the caps to stay pushed into the objectives, but it’s a minor niggle.

The case for the new 10x56 SLCs is the same as the ELs’.

Swarovski’s new 10x56 SLCs with strap and caps.

In Use – Daytime

Ergonomics and Handling

The modest size, graduated thumb indents and comfortable armour make these a delight to handle.

Yes, they are larger and heavier than mid-size birding binoculars, but they aren’t the unwieldy monsters that many big-objective binos (including the older SLCs) are. They don’t look ridiculous hanging around your neck either, though compared with 10x42s you would really notice the extra weight carrying them all day.

The focuser is one of the very best: perfectly weighted and completely smooth, it’s fast too: from closest focus (a few metres) to infinity takes a single turn. Following birds in flight is completely intuitive and easy. The focuser is smoother and faster than Zeiss’ 10x54 HTs’.

The dioptre adjustment is excellent. Swarovski have adopted the mechanism from the ELs and it’s an improvement over the old SLCs’ - perfectly weighted with precision click-stop adjustment.

Comfort at the eyepiece is outstanding, due to the large eye relief and lack of blackouts. There is enough eye relief to accommodate almost any specs, but the multi-position eye cups make comfort for everyone else perfect as well. Once again, eye relief is slightly better than Zeiss’ 10x54 HTs on my ruler.

Handling and comfort of the 10x56 SLCs is outstandingly good.

The 10x54 HTs are easy to hold, even for small hands. Ergonomics are first-rate.

Swarovski’s new 10x56 SLCs are more compact than the old model, but they’re quite a bit larger than the 50mm ELs.

The View

My first impression of the daylight view through these is amazement. They are stunning in every way – not the lacklustre daytime view of many big-eye binoculars at all.

As I’ve explained in other reviews, big objective lenses don’t mean bright views in full daylight. This is because during the day your pupil contracts and so your eye can’t make use of all the light the lenses collect – they effectively stop a 10x56 down to say a 10x30. This means the quality of the view in bright daylight depends on the percentage of light the optics transmit and their quality, not the objective size. Due to the difficulty of making larger, higher power optics, binoculars like these 10x56s often have a worse daytime view than smaller models! Not these.

Daytime brightness is just outstanding: if anything better than the Zeiss 7x42s which I’d previously rated best and much brighter than Swarovski’s old 56mm SLCs. That’s an amazing result for a big-eye binocular. Zeiss claim a slightly higher light transmission percentage for the 10x54 HTs, but these Swarovski SLCs seem every bit as bright.

Everything else about the view is fabulous too. Optical quality and focus snap are of the very best. The colours are vivid and natural. Sharpness and resolution is peerless. Stray light is almost perfectly suppressed: viewing as close as I dare to a low Sun yields no ghosts or washout.

The big lenses have unexpected payoffs too. I follow a Robin from my patio into a dense thicket of branches, lost in the gloom to the naked eye. The winter sun is already down and the garden is full of deep shadow. This would be a challenging situation for most binoculars, but the 10x56s keep showing every rusty feather.

I spot a woodpecker on a high branch maybe 150m away, silhouetted against a brilliant dusk sky, but I can still see the red in his plumage – HD indeed.

Swarovski’s new 10x56 SLCs have a daytime view as good as, or better than, any mid-size birding binocular I have tested. I just wanted to keep using them, they’re that good.

In many ways the daytime view reminded me of the Zeiss 7x42 FLs: vivid, sharp and amazingly bright.

Flat field?

The field may not be quite as wide as Zeiss’ 10x54 HTs, but it’s flatter and other aberrations (coma and astigmatism) are very well controlled, even at the field stop. Field flatness is inferior to Swarovski ELs, though and inferior to the 15x56 model too, for some reason.

Chromatic Aberration

Chromatic aberration (false colour) suppression is better than any binoculars I have ever tested. Even my stiffest test – viewing roosting Jackdaws and Crows in high branches silhouetted against a clear sky yields almost no false colour and even focusing through produces no fringing. For the first time the view through these is like that through a small apochromatic refractor.

At last, you can enjoy birds in flight (or indeed aircraft, if that’s more your thing) against a bright sky with no green or purple fringing to mar the view.

Chromatic aberration is another area where these new SLCs better Zeiss’ 10x54 HTs and indeed the 12x50 ELs I tested.

In Use – Dusk

With 93% transmission, 56mm objectives and a 5.6mm exit pupil you would expect the 10x56 SLCs to have outstanding dusk performance and they do. These allow you to pull detail out of shadows that have already become black and featureless with night drawing in. Looking at the copse across the fields, the ground under the trees still looks like daytime when all is impenetrable darkness with my naked eyes.

The high optical quality and accurate focuser make focusing in low light much easier than many binoculars.

A bright dusk sky causes problems for some binoculars, flooding the objectives with light and washing out the view. The 10x56 SLCs have deeply recessed objectives with a small matt-black band around the objective rim to control ghosting. They just don’t suffer from this issue.

If you go birding or nature viewing at dusk, or if you go owling in full darkness, these are superb binoculars. Note that they may work better for older eyes than an 8x56, which has a larger exit pupil than most older eyes can accommodate.

In Use – The Night Sky

A combination of high transmission Abbe-König prisms, the best coatings and big HD objectives should make the 10x56 SLCs ideal for astronomy. As expected, they show rich star fields full of dimmer stars and pick out dim DSOs with ease. Many consider 10x ideal for astronomy, and though I generally prefer 12x, I have to admit that 10x is easier to hold steady whilst still pulling in smaller objects – clusters and nebulae. I like the wider field too – it gives more ‘context’.

I couldn’t force any ghosts or spikes out of these under any conditions.

The Moon

A magnification of 10x is low for the Moon, but the 10x56 SLCs deliver a near perfect view of it: hard, sharp and full of detail. Stray light suppression is excellent, so even a bright Moon produces only a trace of ghosting in-field. When working around the Moon (or streetlights) ghosts aren’t a problem.

Even a bright full Moon gives almost no false colour.

I enjoyed superb views of a 27 day-old crescent one morning, with lots of detail despite the difficult, low-contrast phase and bright dawn sky.

Venus

I have yet to see prismatic optics that give a completely flare-free view of Venus, but the 10x56 SLCs come close. Venus was small and gibbous when I viewed it and showed a brilliant ‘star’ with no significant flare and no nasty ‘spikes’ of light or chromatic aberration.

Jupiter

Jupiter can mean trouble for mediocre binoculars because the tiny, bright disk causes flare or spiking in the prisms. However the 10x56 SLCs produce a clean view of Jupiter – just a tiny hard cream ball with minimal flare. All four Galilean satellites were easy to resolve on either side of the planet. The excellent contrast gave a great view of Jupiter even in a bright dawn sky.

Deep Sky

I generally prefer a bit more than 10x magnification for finding and viewing smaller deep sky objects. Nonetheless, those big lenses and high-transmission optics give very bright deep-sky views, whilst the larger field and steadier view make them easier to use than my 15x56s.

Open clusters are a real strength of these binoculars. Stars are tight and bright across most of the wide field. The Double Cluster was full of brilliant stars, much more populous than through smaller binoculars. The Pleiades gave a very pleasing view of brilliant blue-white stars and a hint of nebulosity with no false colour.

The string of open clusters in Auriga were brighter and more sharply defined than through most binoculars. M38 showed its characteristic cross-shape and lots of faint stars with averted vision. Both M36 and M38 fit easily in one field.

Albireo was an easy split, despite the low power. The big objectives and high-quality optics mean star colours are unusually strong; Albireo’s colours really burn.

The Great Nebula in Orion looked bright and detailed, with a sense of the extending arms of nebulosity that only larger objectives give. Most of the sword and belt region fitted in the field together, giving great context that reminded me what I like about lower power views.

The view of M31 was especially good, with lots of field width to fit the whole galaxy in, but plenty of brightness to deliver a hint of the dark-lane cut-off on one side and a definite sense of the extended spiral arms with bright core rather than just the usual blob. M33 also looked especially bright and defined.

Perhaps the most exceptional view was simply the Milky Way star fields between Cygnus and Cassiopeia, where the field is filled with zillions of diamond-dust stars in a way you just don’t get with higher powers or smaller apertures.

The news is slightly less positive with smaller DSOs. The globular cluster M15 was easy to find but less interesting than with a higher power, ditto the Dumbbell Nebula. I struggled to make a positive ID on M57, the Ring, due to the low power.

The field curvature is noticeable when viewing star fields, but isn’t as intrusive as it was with the Zeiss 10x54 HTs.

Overall, these give the best astronomical views I’ve had from 10x binoculars. Though a higher power would give better views of small DSOs, the wide field of these 10x56 SLCs makes for easier handling and better views of star fields and open clusters.

Testing the 10x56 SLCs at night.

Swarovski 10x56 SLC vs Zeiss 10x54 HT

Swarovski 10x56 SLCs and Zeiss 10x54 HTs.

I’ve made a number of comparisons with the 10x54 HTs throughout this test; I’ll summarise them here:

· The Swarovski SLCs have a plainer but ultimately better external build quality and nicer armour.

· The Swarovski SLCs have a smoother, faster focuser.

· Swarovski SLCs have even more eye relief and a better, more precise dioptre mechanism.

· The Zeiss HTs are ~120g lighter but no more compact.

· The Zeiss HTs claim slightly higher transmittance at 95% vs 93%.

· The 10x56 SLCs have larger objectives that gather 7% more light. I think this difference is detectable at night and in deep dusk conditions.

· The Swarovski SLCs suffer less from false colour (they are virtually free of it whilst the HTs still have some).

· On paper the Zeiss HTs have a slightly wider field.

· The Swarovski SLCs have a flatter field and less off-axis aberrations, so their usable field width is greater.

· Not a big deal perhaps, but the Swarovski SLCs have a more upmarket case.

· The HTs are more expensive.

I prefer the Swarovski SLCs to the Zeiss HTs in almost every area, though the differences are fairly subtle.

Swarovski 10x56 SLC HD vs Zeiss Conquest 10x56 HD

Zeiss Conquest 10x56 HDs and Swarovski 10x56 SLC HDs: Zeiss are bigger and heavier.

If Zeiss’ 10x54 HTs are more expensive than the SLC HDs, the Conquest HDs are about the same amount cheaper. I really like the Conquests, but the how do they compare to the SLCs? A summary of the main differences follows.

· The SLCs are about 100g lighter.

· The SLCs are about 1cm shorter in length.

· The Conquests lack thumb cutouts but are still comfortable to hold.

· The SLCs have a slightly brighter view, but the Conquests are still a very bright binocular.

· The SLCs have less chromatic aberration (i.e. essentially none) centre field and much less towards the field stop.

· The Conquests have a visibly wider field, but aberrations – field curvature, coma, astigmatism and false colour too – increase more off-axis than the SLCs’, so usable field is no more, perhaps less.

· The SLCs are subjectively slightly sharper and higher in resolution.

· The SLCs have much more (4-5mm) eye relief in practice and so are better for specs wearers.

· The Conquests’ focuser is just as smooth and accurate, but has a touch of free-play the SLC’s doesn’t.

· The Conquests produce faint flare spikes and ghosts from bright artificial lights in-field that the Swaros don’t, but not enough to spoil the view.

· The Conquests’ dioptre adjustment is markedly inferior.

· The Conquests’ eye cups are rougher in action and poorer quality.

· The Conquests’ armour is smoother and less pleasant to my hands, much easier to mark.

· The Swarovskis feel like a slightly higher quality product (but this is subjective).

· The Conquests are currently about 25% cheaper

Overall, I prefer the Swarovski 10x56 SLC HDs, but apart from the Conquests’ off-axis aberrations, the differences are again subtle. Whether the Swarovskis are worth the extra cost is up to you.

Summary

Along with Swarovski’s ELs, these new SLCs share the distinction of being the most perfect binoculars I have ever tested.

The view is wonderful: super bright, wide, pin-sharp, full of detail, with almost no false colour. The mechanics of these binoculars are top-drawer too. The focus and dioptre mechanisms are spot on, absolutely precise and smooth. Build quality is beautiful. The ergonomics are remarkably well thought out for a big-eye binocular; they feel great in the hand with excellent armour that is grippy but doesn’t attract finger marks and dust (Zeiss take note). The focuser is among the best out there. Eyepiece comfort is peerless with masses of eye relief, no blackouts and multi-adjustable eye cups.

Unlike most big-objective binoculars there are few downsides to Swarovski’s 10x56 SLCs. The daytime view is like the finest premium mid-size models. And yet at dusk or at night their big objectives and high-throughput design deliver much more brightness than any smaller binoculars. They’re really quite compact too. The only caveat is that they might well be too heavy to carry all day if you’re birding on the hoof. Apart from that, these could be your only binoculars, fantastic for anything you care to use them for: static birding, owling, spotting and of course … astronomy.

Perhaps the only tiny downside is a bit of field curvature from 75-80% field width. But given that the field is very wide this isn’t a huge problem, even for astronomy where off-axis aberrations are always most noticeable. They are much better than the 10x54 HTs in this respect, but I still prefer the ELs’ flat field.

The difficult question is whether you go for these or a pair of 50mm ELs. Yes the ELs are lighter and more compact and the double barrels are a bit easier to hold too. The ELs give you the option of 12x, which I still prefer to 10x for astronomy. And I much prefer the flat field of the ELs. But the SLCs are brighter day or night, have more real eye relief, slightly less false colour and a smoother focuser in my sample; they’re cheaper too. Meanwhile the SLCs suffer no compromise in design or manufacturing quality that I can see. It may simply come down to what you prefer looking at. Like the Moon and smaller DSOs? Buy the 12x50 ELs (or the 15x56 SLCs). Enjoy open clusters and surfing the Milky Way? Go for the 10x56 SLCs.

The Swarovski 10x56 SLCs share my ‘favourite 10x binocular’ tag with the 50mm ELs. Which would you choose? Up to you! It’s a nice problem to have.