Are Zeiss’ range-topping SF birding binoculars just a belated copy of Swarovski’s revolutionary ELs? In this review, I put them to a thorough test to find out.

Zeiss Victory 10x42 SF Review

The ‘Alpha’ European binocular manufacturers, and to some degree Nikon too, are locked in an eternal arms race, vying to outdo one another with every new model.  I’m not complaining. That competitive situation pushed Swarovski to release the best binoculars in the world for some years – their Swarovision EL range.

To me the EL SVs were a major leap forward – the first roofs to equal or better the very finest porros and one of the first binoculars I found hard to criticise. I imagine they caused a major headache for Zeiss et al.

I’m guessing that the response from Zeiss – these SFs – produced some smug faces in the Swarovski boardroom, at least at first. After all, imitation is the sincerest form of flattery and the SFs are clearly just EL clones. Or are they? Actually, as we will see, the SFs’ EL-clone appearance hides some serious innovation.


At A Glance



Objective Size


Eye Relief


Actual Field of View


Apparent field of view

64 degrees

Close focus



92 %





Data from Zeiss Europe.


What’s in the Box?

Packaging is classy and typical of recent Zeiss binoculars.


Design and Build

The SFs are an all-new model, owing virtually nothing to earlier Zeiss premium lines like the Dialyts and FLs. Their slim open-bridge design seems a clear admission that Swarovski got the ELs so right that Zeiss had no option but to copy them. But as I hinted in the introduction, appearances are deceptive in this case.

The SFs are currently (early 2016) only available in two versions, the main birding sizes of 10x42 and 8x42. I would eventually expect to see at least 8x32 and 10x32 SF models joining them to replace the older Victory FL in those sizes.

Body and Ergonomics

The first thing you notice about the SFs is how long they are. This will turn out to be part of that radical thinking I mentioned before, but for now it’s a bit puzzling. To put this rather stretched design into perspective, the 10x42 SFs are almost exactly the same length as Swarovski’s ELs – the 10x50 ELs! They are longer than almost any other 42mm binoculars, a whopping 30mm longer than Swarovski’s 10x42 SLCs.

The SFs may be surprisingly large for a 42mm design, but they aren’t heavy. In fact, at 780g they are lighter than many of the competition (100g lighter than the ELs) and they feel it too. That low weight is partly due magnesium construction, partly to the thinner, simpler long focal-length objectives that a longer body allows. However, Zeiss have clearly had to do some weight shaving elsewhere: the armour is thin and the eye cups vague and flimsy.

Talking of the armour, I’m personally not keen on that light grey colour (and yes, it’s a light grey, though some photos show it darker): it’s precisely the same colour as a leather jacket I favoured … circa 1979. A dodgy colour is one thing (Zeiss have recently reverted to black), but the armour also has a smooth finish that marks easily. More seriously, the armour on the test pair was loose in places, making scrunching noises when pressed.

The body barrels are plain tapered tubes and don’t have the thumb indents you get with Swarovski’s ELs, but you will naturally hold these around the barrel ends, just like the guy in the promo’ photos, so arguably that doesn’t matter.

Despite the light-weight feel, the SFs are of course fully waterproof and nitrogen purged like any Zeiss binoculars.


Left to right: Swarovski EL 10x50, Zeiss SF 10x42, Zeiss Victory FL 7x42.


The focuser has an oversized wheel that has been moved forwards in the bridge to reduce finger spread in the hold. The focuser is very smooth, with a light action and no play. That lightness gives a more intuitive feel than the weightier focus action on a pair of Swarovski ELs, coming closer to my favourite focusers of all – those found on Nikon’s EDGs and HGs. The SFs’ focuser takes 1.5 turns from close focus to infinity, but because the SFs focus so close (1.5m) it’s as fast as most focusers that take a single turn.

Dioptre adjustment on the SFs is by a separate knob at the front of the bridge, which you pull out to adjust. The mechanism has a centre click stop but no others and no scale. The action feels slightly coarse and the knob is wobbly and flimsy. The dioptre mechanism on Swaro’s ELs is much better – much more solid and precise with quarter dioptre click-stops and a scale that lets you dial in your difference in prescription.



Dioptre adjustment is via a separate wheel at the front of the bridge – pull out to adjust.

Optics - Prisms

Given that Zeiss are famous for using the Abbe-König type of roof prism that needs no mirror coatings and so has a higher level of light transmission, it seems strange that these SFs use the more common Schmidt-Pechan type roof prism. Especially strange because the main reason for not using Abbe-Königs is that they take up more space length-wise and yet if these SFs have anything it’s spare space in the length department. Perhaps it’s to do with achieving that rearwards balance point.

When it comes to mirror coatings these have the latest dielectric ones like most premium binoculars these days and Zeiss’ claim of 92% transmission is still up with the best (perhaps achieved with fewer optical surfaces – see discussion below).

Optics - Objectives

The SFs have a simple three element (two plus focusing lens) objective design, compared with the more normal triplet plus focusing lens. I suspect that to achieve this, Zeiss have employed a larger-than-usual focal ratio for the SFs’ objectives. Aberrations decrease with longer focal ratios so fewer, thinner elements with shallower curves suffice.

The advantage of this approach is that the objectives are lighter in weight (78g lighter than the HTs’ objectives, according to Zeiss), throwing the balance point towards the eyepieces and improving handling. And this at last also explains why the SFs are unusually long – a longer focal ratio of course means more space required between objective and eyepiece.

The objectives are described by Zeiss as ‘Ultra FL’. This means the best ED glass (in this case apparently from Schott), but also that two of the elements employ special glasses, instead of the usual single ED element found in most HD binoculars. In this case, there is a single ED element in the main objective plus another as the focusing lens. This should give near perfect correction for false colour.

Coatings are the familiar dark pink Zeiss T* variety. These are some of the very best coatings around and despite the lossy Schmidt-Pechan prisms they give the SFs a very bright view.

The focusing assembly contains a knife edge baffle and careful blacking to counter stray light, but there is no blackened lens ring, unlike almost any other recent premium binocular. Given the light colour and shiny surface of the armour, this seems a strange oversight.

In my pair, the left hand focusing assembly contained a lot of dust which is another clear manufacturing fault.

Zeiss Victory Objectives, SF and FL: coatings are similar, but note the steeper curves on the shorter focal-length FLs’.

Focuser assembly includes a knife-edge baffle, but note no blackened lens ring.

The left-hand focuser assembly contains a lot of dust on this pair.

Optics – Eyepieces

If the objectives are a simple design by modern standards, the eyepieces are the opposite – a complex design with seven elements, including a field flattener, they allow Zeiss to offer the full wish-list of features: plenty of eye relief with a very wide and well-corrected field. Zeiss have used these complex eyepieces to their advantage in another way too – they are 60g heavier than the HTs’ eyepieces, helping throw the balance point backwards.

Actual field of view is 120m at 1000m, giving an apparent field of 64°. That puts these SF eyepieces into wide-field astro’ eyepiece territory.  By comparison, Swarovski’s 10x42 ELs have a field of 112m at 100m, which translates to a noticeable four degrees less apparent width.

I measured eye relief at 18mm from the rim of the cup – exactly as claimed and very good, so I can comfortably see the whole field with glasses on. That’s a critical few millimetres more real-world eye relief than the ELs (even though Swarovski claim 20mm for them).

That much eye relief often comes at the price of spherical aberration of the exit pupil which causes blackouts as you move your eyes around. However, the SFs are essentially free of blackouts.

If the eyepiece characteristics are of the very best, the eye cups are not. Compared to the precise and solid cups on a pair of ELs, the SFs’ are slightly loose and squashy and vaguer of action. Early models like these had just two positions; the later ‘Black’ model has three.

Eye cups have just two extended positions that I could find (revised ‘Black’ model from late 2016 onwards have three).


At last Zeiss have provided the SFs with a high-quality semi-rigid case to compete with the field case Swarovski now ship with all their binoculars. The Zeiss version is usefully slimmer than the Swarovski equivalent, with a more tailored fit, but still has a protective plush interior and separate accessories compartment. One slightly strange feature is a closing strap with magnetic catch as well as a zip – why?

The strap and caps are familiar recent Zeiss. The objective caps push in and are kept captive with a lanyard.



Field case is a quality item.


In Use – Daytime

Ergonomics and Handling

We’ve seen how Zeiss have used light objectives and heavy eyepieces to shift the SFs’ balance point backwards. Zeiss call this their ErgoBalanceTM concept. That rearwards weight bias is very apparent and really works for me, helping to reduce fatigue when viewing for long periods. Handling is consequently outstanding. The barrels are long enough that holding around the ends feels natural and helps reduce shakes. For me this makes the lack of thumb indents irrelevant. That smooth, thin armour feels slightly less comfortable than Swarovski’s though.

The SFs feel light and handy and their length isn’t a problem for me. In fact, that extra length makes them easier to hold than a very compact 10x42 like Swarovski’s SLCs, but obviously bulkier for travel.

The focus wheel is large enough to operate with gloves. I can easily reach it with my forefinger, even when gripping the SFs around the front of the barrels, because Zeiss have moved it nearer the objectives. The focuser’s action is near perfect – smooth and light, yet precise and fast. The dioptre mechanism is effective, but less ideal.

Eyepiece comfort is outstanding, with lots of eye relief for specs wearers, but minimal nasty blackouts for the rest who view without.

The SFs look quite elegant when worn, that grey armour notwithstanding, but much larger than some 10x42s.


Swarovski 10x42 SLCs for comparison: much more discreet than big Zeiss Victory SFs

The View

The view is amongst the very best: bright, detailed and very sharp. Focus snap is superb. The colour balance overall seems slightly less vivid than Swarovski’s ELs and I also felt that the SFs lacked the absolutely crystalline clarity and supreme resolution of my ELs, but that could well be down to variation between samples. By any standards, the view is excellent: superbly detailed and natural and aberration free.

One metric by which the SFs really beat the premium competition is field width. The increase in actual width over the ELs’ may be only 7%, but that equates to about 15% in area and it’s certainly noticeable. I have long been hoping for binoculars that give the expansive view of a wide-field astronomy eyepiece, where the field stop retreats into peripheral vision; the SFs give a taste of that effect.

Interestingly, the actual field width of the 10x42 SFs comes close to that of some 8x42 binoculars and so if you can manage the extra shakes there is less reason to go for the lower power. I watched a buzzard circle in the far distance in a way that would have been a struggle with less magnification.

Typically for Zeiss, depth of field is really excellent - right up there with the best and perhaps even a little better than my ELs.

The SFs focus closer than just about any other binocular. This makes them wonderful for examining flowers and insects, but be aware that you may have to strain to merge the images below about 2.5m.

Taken as a package, the SFs’ optical characteristics are amongst the very best.

Flat field?

The SFs’ eyepieces include field flatteners and so the field is certainly usable to the very edge, unlike say a pair of Victory FLs’. However, the field is not completely flat – less so than Swarovski’s ELs’ or Nikon’s EDGs’ for example. The field drops off more sharply towards the very edge than the ELs’ as well. Star testing reveals some slight astigmatism in that last 5% too.

This mild off-axis softening is no accident: Zeiss have deliberately introduced a little distortion and field curvature for comfortable panning.

Overall, though, field flatness is good and the impression is of a well-corrected field of view.

Chromatic Aberration

The SFs show slight residual chromatic aberration in very high contrast situations, but otherwise they are free from false colour in normal use. In this respect they are about same as Swaro’s ELs and other recent premium HD designs.


In Use – Dusk

Dusk performance is excellent, the bright optics delivering deep shadow penetration. The 10x42 SFs even work really well in bright Moonlight and I was able to go searching for a noisy local owl at Midnight. I also spotted one of the blacked-out Special-Forces Hercules aircraft that regularly fly close to our house at ultra-low-level, with the bright optics and high contrast making it easy to pick out of a dark sky.

The very high optical quality makes these easy to focus in very low light – something lesser binoculars often fail to do.


In Use – The Night Sky

Despite the lack of a blackened lens ring, the SFs control stray light exceptionally well. They produced no flare or ghosting or spikes, even on a streetlight or full Moon. Veiling flare, when viewing around a full Moon or bright lamp, was also very well controlled.

Stars are very sharp on axis, but distort a little starting at 70% or so. Contrast is excellent.

I found that the SFs low weight, rearwards balance point and long barrels made them unusually comfortable for long astronomy sessions.

The Moon

The 10x42 FS deliver the sharpest of Moons, with no false colour or ghosting even at full Moon. The Moon was very detailed and crisp – one of the very best views I’ve had through lower powered binoculars (i.e. less than 12x), with lots of the larger craters clearly identifiable.


The SFs generated no flare or false colour on Jupiter. The Galilean moons appeared as very distinct, sharp stars, easily picked out even when close to the planet.

Deep Sky

The wide, flat field and pin-point stars, along with high-transmission optics, mean the 10x42 SFs punch above their weight on deep sky. Star fields are brilliantly populous and nebulae bright and well-defined for the aperture. I had great views of the sword area of Orion and the open clusters in Auriga, of brighter galaxies like M31 and M33 too.

Placing both the belt stars and sword region of Orion in the same field, Mintaka at the far right of the belt and Nair al Saif at the bottom of sword remained star-like. Many binoculars spoil this view by distorting those edge stars with field curvature and astigmatism.

Although the quality of stars falls off a little towards the very edge, the SFs don’t create the ‘tunnel’ effect of blurred stars in the outer field which many Zeiss binoculars do.

The 10x42 SFs were designed as birding binoculars, but they make great astronomy binoculars too.


Zeiss 10x42 SF vs Swarovski 10x42 EL

I have been comparing these two similar but competing models throughout this review, but I’ll summarise their relative strengths and weaknesses here:

·        The view is basically very similar: wide, bright, sharp and detailed.

·        Levels of false colour are much the same too (i.e. low but not quite absent).

·        The SFs have a slightly wider, but also slightly more curved field.

·        The SFs have more real-world eye relief and are better for specs wearers as the result.

·        The SFs are longer, but substantially lighter in weight.

·        The SFs have a centre of gravity closer to the eyepieces that I found more comfortable for long periods of viewing.

·        The SFs’ focuser is lighter and smoother.

·        The ELs’ dioptre mechanism is more precise and feels more robust.

·        The Swarovskis have palpably better build-quality.

Overall – and ignoring build-quality – I slightly prefer the SFs for their lighter weight, lighter focuser and wider field.



The management summary of the SFs is that they are probably my favourite ever binoculars in use, edging just slightly ahead of Swarovski’s ELs in terms of field width, eye relief, focuser and handling. They do have a slightly more curved field than the ELs, with a little astigmatism at the edge that the ELs don’t have, but the compensation is that wider view; it’s a trade-off I’d be willing to make. Other aspects of the view are very similar to the ELs’, i.e. among the very best.

Given that these SFs have among the best view and handling of any 42mm binoculars I’ve tested, you might imagine I’ll be rushing out to buy a pair. But I won’t be. And I’m not sure I’d recommend you to either. Why? In a word: quality.

You could dismiss the loose armour as a simple QA fail. But then there is all that dust in the left barrel. Even ignoring that, there is evidence of poor build-quality elsewhere: the loose eye cups, the uneven finish on the bridge, the loose and wobbly dioptre knob. Overall, these minor issues add up to a level of quality that just isn’t good enough in binoculars costing this much. I would put this down to a Friday afternoon example, but for the fact that several Zeiss binoculars I’ve reviewed recently have had less than perfect build-quality too.

I really loved using the Zeiss SFs. Based on their performance – view and handling – alone, these might well be the best binoculars I have ever reviewed. But their build quality just isn’t good enough and so I’d struggle to recommend them (at least based on this pair, anonymously bought new).

Updated by Roger Vine 2018.