The old Swarovski 15x56 SLCs were my favourite hand-held astronomy binoculars. The latest model has been radically re-engineered with the latest technology. In this review I find out if it’s still a favourite.
Swarovski 15x56 SLC HD Review
For some years, Swarovski’s older 15x56 SLC was my favourite hand-held astronomy binocular. It was flawed in some ways – big and heavy, with too little eye relief and too much false colour – but when it comes to finding and enjoying small DSOs it beat all comers.
Swarovski themselves admitted my old 15x56s were a fifteen-years-outdated design, so they were due for an update to bring them in line with the smaller SLC models. What the 56mm SLCs actually got, though, was a significantly more radical re-design that moves them into the high end.
Let’s find out if they’ve really improved the old 15x56 SLC, or compromised on its peerless optical quality in order to make it more compact.
At A Glance
Actual Field of View
Apparent field of view
Data from Swarovski
What’s in the Box?
This is the third pair of Swarovskis that I’ve seen with this new box style. The box is flatter and a brighter green. The Inner has an embossed Swarovski logo and a rather lovely painting of a hawk soaring over an Alpine peak on the inside of the lid. I originally thought this was a European version, but no it’s an official UK import. I guess it’s to compete with those classy Zeiss boxes. Of course, you and I are much too sophisticated to be swayed by such blatant marketing … aren’t we?
Contents of the big white Swarovski box: 15x56 SLC HDs and accessories
Design and Build
The older SLCs were a 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:
· HD lenses to curb chromatic aberration (false colour fringing).
· Abbe-König prisms (like Zeiss HTs, FLs and Dialyts) to improve light throughput and brightness.
· Longer eye relief to allow a full-field view with spectacles.
· A significantly shorter, slimmer design.
· A new focuser and dioptre mechanism, like their other premium designs.
In other ways the new SLC 15x56 looks conventional, with a stubby aluminium body and a conventional bridge, not an open one like the ELs.
Body and Ergonomics
The 15x56 SLC HDs 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 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 recent Zeiss armour. These new SLCs are shorter than the Zeiss Conquest 15x56s - about the same length as the Zeiss 10x54 HTs and Nikon’s Monarch 16x56s. The SLC HDs are lighter than the Conquests and Monarchs too, but heavier than the HTs.
Build quality is typical Swarovski – flawless and excellent, identical to the more expensive ELs. Styling is plainer than the Zeiss 10x54 HTs’.
The only criticism I could make of the body is the rather plasticky hinge, which looks lower rent than the metal hinge on an EL.
Overall, though, this is a typical Swarovski – plain, but beautifully functional engineering.
These are the most ‘high-end’ big-eye binoculars currently on the market.
Swarovski 15x56 SLC HD, Zeiss Conquest 15x56 HD and Nikon Monarch 5 16x56 HD
The focuser is oily-smooth and precise with absolutely no play or stickiness, but a bit heavier than the Els’. The feel of the focuser is the same as the 10x56 model, but seems slower at almost two turns to go from closest focus to infinity. I guess that this model is expected to be used on static targets, not birds on the wing. Accuracy and smoothness are faultless, but I’m not sure I don’t prefer the lighter, faster feel of a Zeiss HT or Conquest.
The dioptre adjustment is the best around and can easily be done one-handed: snick out the focuser wheel for a click-stop mechanism with an accurate scale.
New SLC focuser is much like the ELs’: Pull to adjust the dioptre
Optics - Prisms
Like the other 56mm SLC HDs and Zeiss Victory HT and larger Conquest models, these have Abbe-König prisms, different from conventional Schmidt-Pechan prisms. Different how and why? Well, Abbe-König prisms are longer and thinner, allowing a more tapered body design. More significantly, Abbe-König prisms don’t require mirrors (no SWAROBRIGHTTM dielectric coatings needed) – they bend the light by total internal reflection and so transmit slightly more light as the result. Swarovski claim 93% transmittance with these, compared to about ~90% for the very best conventional roof designs like their EL models.
Abbe-König prisms do make for a brighter binocular; all the brightest roof-prism binoculars I’ve tested have them.
Optics - Objectives
Swarovski’s premium range, the EL, contain 24 optical elements. Remarkably you might think, these 15x56 SLC HDs have even more - 26 optical elements. So where does all that glass go, then? One possible answer is the objectives, in order to deliver a short body and freedom from aberrations. Another possibility is that these in fact have field-flatteners (see the discussion of field flatness below).
Swarovski don’t publish details of the lens design, but given that claim of 26 optical elements and (as we will see) given the outstanding false colour correction, these probably contain two or more HD elements made of high-fluoride glass, as the Zeiss HTs do.
The SLC HD range don’t boast premium SWAROVISIONTM technology like the ELs’ and their coatings have a pink reflection where the ELS’ is greenish. Strangely, to me, the coatings on the SLCs look more transparent, less reflective.
The barrels incorporate knife-edge baffles to control stray light and internal build quality appears good and rugged.
No SWAROVISIONTM tech’ for the SLCs (right), but their coatings actually look more transparent than the Els’.
Optics - Eyepieces
These SLC HDs clearly have a complex eyepiece design. The eye lenses are about one millimetre smaller than the ones on the 10x56 model, but much larger than the old 15x56s’. Compared to the Els, the eye lenses are much smaller and a very different design, though (see below).
These eyepieces give improved eye relief and a larger field (4.5 degrees vs 4.1 for the old model). That’s a wide field, but not as wide as the Zeiss Conquest 15x56s’, which come close to the field width of some 10x binoculars, albeit with more off-axis aberrations than these Swarovskis.
The exit pupils look properly round and un-vignetted; internal reflections are well suppressed.
Eye relief is claimed to be 16mm, but I measured 14mm from the rim of the eye cup. So these have a lot less eye relief than the 10x56 model and the whole field isn’t quite visible with my glasses on. No compact high-power binoculars have generous eye relief and these SLC HDs still have more than the older model and as much as a pair of 56mm Zeiss Conquests, even though they claim to have 18mm.
Kidney-bean blackouts as you move your eye around (technically known as spherical aberration of the exit pupil) are non-existent, which is good news.
Multiple click-stop eye-cups are provided and they work well, but are not oily smooth and damped like the Els’. The cups are slim – good for people with close-set eyes.
15x56 SLC HDs have smaller eye lenses than the 10x50 Els.
Swarovski’s usual multi-adjustable and very solid eye cups aren’t quite as oily-smooth as the Els’.
These are the Zeiss 15x56 Conquests’ eye cups for comparison – poorer quality and thicker, ruining their potentially better eye relief.
The UK model now gets a slimmer padded field case, plus the usual ‘lift’ strap and lens cloth. Objective caps are the band-on type and work well enough. The eyepiece cap is hinged and fits very snugly over the cups. Swarovski make a very high quality tripod adapter (see discussion below), but it’s a costly accessory (Zeiss give you one for free with the 15x56 Conquests). Other possibilities include an iPhone adapter for taking snaps through the binos.
To fit the adapter, you first need to pop the cover off the front of the hinge and screw-on a lug on the front. This is tricky to do – you have to set the hinge to its widest and then prise the cap off, revealing the thread for the adapter lug. The cover is plastic and you’re almost bound to have to use a screwdriver which risks damaging it (no UK coin is really small enough, I used an old Dutch coin here). Then you screw on the lug with the provided allen key and tighten down a set screw to stop it shifting.
Once fitted, the lug just slides into the adapter and a flick of the lever locks it in place. It’s an elegant and efficient solution.
Fitting the tripod adapter lug is a fiddly process
Swarovski’s tripod adapter is a classy thing, ‘Made in Austria’. But it’s NOT included!
Once the lug is fitted, mounting the big Swaros on a tripod is quick and foolproof.
In Use – Daytime
Ergonomics and Handling
The sculpted body falls naturally to hand. These are comfortable to hold. I like Swarovski’s armour – it’s grippy, warm, hypoallergenic and doesn’t smell of rubber; it doesn’t attract dust either.
This new version feels much smaller and lighter than the old one, but there is still space to put your hands around the objectives for steadying them when you don’t need quick access to the focuser.
Slightly tight eye relief is really the only downside to these binoculars. I can’t quite see the whole field with my chunky retro-framed specs and you might not be able to either. The eye relief is still better than the old model’s, though.
These look big hanging around my neck, but I wouldn’t feel quite such an idiot walking up the local fell with them on a sunny Sunday as I would have with the old model.
Despite the cutouts, holding around the barrels is still the most natural way to damp those high-power shakes
The new SLCs don’t look as enormous hanging around my neck as the old model, but they’re still a big binocular.
These don’t have the immediate ‘wow’ factor of the 10x56 model’s view, but that’s simply because the real width and depth of field are tight due to the high power. Once you’ve got over that, the view is really excellent – bright, sharp and full of detail, so much better than the old model’s.
Again, I need to point out that daytime brightness isn’t due to the big lenses. Your pupil contracts during the day and so stops the optics down to perhaps a 15x30 or 15x20. Under these conditions brightness is down to the transmissivity of the coatings and prisms. The Abbe- König prisms make a noticeable difference here compared to the older SLCs or other big-eye binos that use roof prisms, like the big Nikon Monarchs.
Optical quality is supreme – both barrels have an absolute focus snap that really demands the precise and accurate focuser these have. The focus point is exactly the same focusing in and out, something a lot of lesser high-power binoculars fail at (the Nikon Monarch 16x56s for example).
Both the Zeiss Conquests and the SLC HDs have similar coatings with a pinkish tone. No surprise then that these give the same vivid, but neutral, rendition of colours as the Zeiss.
Put these on a tripod and the daytime view is gorgeous – wide, vivid and full of detail; few scopes manage this kind of optical quality.
Overall, the daytime view is among the very best for a high-power design.
These have almost the perfectly flat field of a Swarovski EL. Field curvature, astigmatism and coma remain negligible and even distortion doesn’t begin to creep in until the last 10% or so. In the daytime that means you could ID a bird at the field stop.
Interestingly, the 15x56 SLC HDs on test here have a flatter field than the 10x56 model.
The view is flat enough to give that ‘rolling ball’ effect when panning.
Below are two photos taken with an iPhone adapter. The first is through the 10x50 ELs. The second was taken through the 15x56 SLC HDs. Note that field flatness is very similar: the 15x56 is just a little less sharp at the very edge.
Swarovski 10x50 EL
Swarovski 15x56 SLC HD
Chromatic aberration is extremely well controlled, really remarkably so for such a high-power, big-objective design.
Tree branches and birds seen against a bright sunny sky are completely free from false colour in focus in the centre of the field. Even when focussing through or panning there is just a trace. The local roof peaks and chimney pots that usually show coloured fringes just don’t with these. The kaleidoscope of false colour fringing you sometimes get when panning through silhouetted branches is completely absent.
Just a little more false colour creeps in towards the edges, in perhaps the last 10-15%. But these show significantly less false colour than the competitor Zeiss Conquest 15x56s, especially off-axis.
The CA performance of the 15x56 SLC HDs is the best I have seen in a high-power model. They are essentially false-colour free in normal use. I really love this feature: it is possible to enjoy birds in high branches with plumage the only colour you see.
In Use – Dusk
These have a very high ‘twilight rating’ due to the large aperture and high magnification, but I personally reckon the 10x56 model is better in twilight. That said, these do penetrate dusk shadows very well if compared to say a 10x42 and have a real light-intensifying effect in full night. I imagine these would be ideal for owling or night hunting.
In Use – The Night Sky
The field is nearly perfectly corrected. A trace of off-axis curvature is noticeable beyond 90% field width, but it is modest. Stars remain star-like all the way to the field stop. There is minimal astigmatism and coma – most of the residual off-axis blur can be focused out. This is unlike a Zeiss Conquest, for example, which has some residual aberrations that can’t be focussed away.
Stars in the broad central sweet-spot are particularly small and tight, giving them extra intensity and brighter colours, helped by the absence of false colour, even on bright O-A stars like Rigel or Vega.
The superb optics and high power suppress Moonlight and sky-glow much better than most binoculars. Aldebaran still shone burningly bright and intensely coloured right by a full Moon.
I was unable to get any ghosting, even from a full Moon. Similarly, veiling flare around a full Moon or streetlight was generally well suppressed. Looking at a bright security light produced no ghosts or spikes of any kind – an outstanding result that confirms the care taken with coatings.
I am used to the high power and generally don’t find it a problem. I rest on my car when I can to reduce shakes, but generally these just show you more.
The Moon nearing full is painfully bright, but still almost free from false colour through the SLC HDs, just hard greys and whites. Resolution is outstanding and I can see a lot of detail, even hand-held: the shadow in Kepler, the Messier twins, the peaks in Copernicus, Schiller near the terminator, the Tenerife Mountains. Mount the 15x56 SLCs up on a tripod and the Moon is stunningly detailed, with all the major atlas features and craters easy to explore, all picked out with perfect sharpness and contrast, like a fine small apochromatic refractor but in stereo (the Moon scudding through icy clouds is mesmerizingly lovely in 3D).
Venus flared just too much to discern a phase, but the level of flare was lower than most. Venus generated virtually no false colour, despite dazzling brightness.
Jupiter showed no smearing or spikes, just a perfect disk with a hint of dark markings (the central belts). The Galilean moons were especially easy to pick out, even near the planet.
The Great Nebula in Orion still showed lots of nebulosity even in bright Moonlight. Similarly, I was able to find the Dumbbell Nebula in a sky flooded by the light of the full Moon.
In general, these repeat the performance of the old model on DSOs – enabling you to pick out and find shape in planetary nebulae and globular clusters you would struggle to find at all with lesser binoculars.
These aren’t just about planetary nebulae, though. The improved real field is plenty wide enough to encompass almost any cluster, helped by the fact that almost the whole field is usable. Clusters just look more populous and interesting, with The Pinwheel and Starfish in Auriga showing their shapes better than through smaller bino’s and with direct vision. In a dark sky, Cassiopeia revealed numerous faint clusters. Meanwhile, the Pleiades are dazzling diamonds, with hints of the nebulosity around them. Bode’s twin galaxies look much more interesting – clearly different shapes – than through most binoculars. Under a dark sky, M42 reveals much more extended nebulosity than through 10x42s.
There is ample field to fit in the whole of M31 as well and again galaxies show more hint of structure than you get with most bino’s under dark skies.
Performance is currently the best available for hand-held astronomy, with the HD optics adding a little extra clarity, contrast and true colour to the already excellent night sky abilities of the pre-HD SLC.
Testing the Swarovski 15x56 SLC HDs in their element – on the night sky
Swarovski 15x56 SLC HD vs Swarovski 15x56 SLC Neu
Here is a summary of the improvements Swarovski have made to the latest SLC 15x56, compared to the (confusingly named) older ‘Neu’ version.
· The HD lenses in the latest version make a big difference by virtually eliminating false colour fringing – during the day, but at night too on the Moon, planets and bright O-A stars.
· The latest version has optics every bit as sharp as the old.
· The field in the new version is both wider and flatter.
· The new version is very noticeably brighter in the daytime, due to those Abbe-König prisms and the latest coatings.
· Overall, the daytime view through the HD model is much more pleasing than the old.
· Eye relief is still a bit tight, but better than the old version and quite usable with glasses (even my chunky specs vignette just the edge of the field).
· The new version is considerably more compact and a bit lighter.
· The new focuser is excellent – a bit smoother than the old model’s.
All these improvements mean the latest Swarovski SLC 15x56 HDs are less of a niche binocular than the old model, whilst retaining the outstanding high-power performance.
Swarovski 15x56 SLC HD vs Zeiss Conquest 15x56 HD
These are very similar, competing binoculars and a comparison is in order. A summary of their relative merits follows.
· The SLC HDs are shorter and 90g lighter.
· The SLC HDs have a narrower (63 vs 69 degrees apparent) but even flatter field.
· The SLC HDs have a couple more millimetres of eye relief –not in the brochure, but in the real world.
· The SLC HDs show significantly less chromatic aberration centre field and much less towards the edge.
· The view through the Zeiss is otherwise as bright, sharp and detailed as the Swarovskis’. Optical fabrication quality is every bit as good.
· The Zeiss focuser is lighter and faster but less oily smooth.
· Some aspects of the Swarovskis – the eye cups and the armour – show higher build quality.
· Zeiss throw in a top-quality tripod adapter.
The Swarovski SLCs are unquestionably the better binocular, but they are also about 30-40% more expensive at the time of writing. I am a perfectionist and would buy the SLCs, but the Conquests are arguably better value.
These new 15x56 SLCs don’t have the quite user-friendly daytime view of their 10x56 sibling – they’re just too high power for that. But these binoculars are still spectacularly good for such a high-power design, the very best I’ve seen and much more usable than most.
Not only are the new 15x56 SLC HDs shorter and lighter than the old model, they have a wider field, almost no false colour and a bit more eye relief too. Optical quality is supreme, beyond criticism. All aberrations are tightly controlled across the field. The apparent field is wide at over sixty degrees, yet field flatness is even better the 10x56 model and approaches other explicitly flat-field designs. In-field ghosting and flare are non-existent. The focuser is a little slow, but silky smooth and accurate.
So the result is a great daytime view – sharp and bright and enjoyable, free of false colour and very detailed. Overall the daytime view is much better than the older 15x56 SLCs, due to the higher transmittance and HD optics which deliver a much brighter, more pleasing image.
But like their predecessors, it’s at night that these really come into their own. Night sky performance is outstanding. In this latest version, the 15x56 SLCs give a wider, flatter view with less false colour on the Moon, planets and bright stars and better eye relief for specs wearers. Like the old model their ability to pull in deep sky detail is unrivalled in hand-held binoculars.
If you can stand the high power (try before you buy!) these are the best hand-held astronomy binoculars on the market and are optically among the finest binoculars I have ever tested (as of early 2017). They get my highest recommendation.