Zeiss SFL 10x40: A Field Review (2024)

My review of Zeiss SFL 8x40 proved so popular ( Zeiss SFL 8x40, A Field Review ) that the thread it generated has reached over 44k hits at the time of writing this, demonstrating how much interest there is in this new series of models from Zeiss. However, there have been several protests that while there was plenty of comment about the 8x40 on the internet, there was much less about the 10x40, hence this new review of the 10x model. Once again, I must thank my contact at Zeiss UK for arranging the loan of this unit so efficiently.

There have occasionally been remarks and questions about why the SFLs are made in Japan. I have no inside information on this, but I am guessing that Zeiss’s sports optics facilities in Mátészalka, Hungary, and Wetzlar, Germany, are fully occupied producing Zeiss’s SF 42s and 32s. In addition, it seems probable that Zeiss’s SFL range will be expanded from the current 40mm models to include 30mm models, so the site of manufacture would need to be able to expand production to accommodate these additional models and would need to be able to achieve the price level targeted by Zeiss. So, it makes sense to me for Zeiss to employ a trusted partner who has the necessary quality, production capacity and cost structure to be able to achieve this.

As usual I will not attempt a forensic technical assessment of the SFL’s optical performance as I am more interested to learn whether they can deliver enjoyable and informative nature observations.

I took the SFL 10x40 to the island of Islay (pronounced eye-la) for a period of 3 weeks during October-November. Islay is situated off the south-west coast of Scotland, about 16 miles from the Scottish mainland and about 36 miles from the north coast of Northern Ireland.

This was our 20th visit to Islay at this time of year, and we have also been 7 times in the Spring, so we know the island very well. Islay is almost split in two, by two sea-lochs: Loch Indaal from the south and Loch Gruinart from the north, and indeed the land connecting these two parts is so low that I am sure that from a distance it could look like two separate islands. The western portion (where we stay) is called The Rhinns and has a distinct flavour of its own, with its west coast facing the open Atlantic Ocean, while the eastern, larger portion, has a long rather sheltered eastern coast, facing across a narrow sound to the Isle of Jura, and across a wider channel to the mainland.

While it may seem that our visit is rather late in the year, it is the time when tens of thousands of geese (Barnacle Geese and Greenland White-fronted Geese) arrive on Islay for the winter, and family groups of Whooper Swans rest and refuel there on their way to Ireland. Plus, there is always the prospect of early winter thrushes such as Fieldfare and Redwing. At this time of year there can also be large flocks of Golden Plover, not to mention the possibility of seeing mother Otters bringing their cubs to the sea for the first time. Indeed we did have the great good fortune to have a sighting of a female and her two cubs quite early during our visit.

SFL 10x40 is priced at around £1600 in the UK, in the EU it costs around €1880, and, in the USA, it is approximately $1800. In the UK it has very little competition at this price point with only Swarovski’s EL 10x42 at around £1690 being near it on price. This 10x40 model is exactly the same length and weight as the 8x40, so that means 640 grams (22.6ozs) and 144mm (5.7in) long, which makes it pretty light and compact. In fact, it is in a similar ballpark to many 32mm models, but of course there is no escaping the 40mm objectives, so it is not quite correct to describe it as the same size as a 32.

When trying the SFL 8x40 for the first time I initially found the focus way too stiff although it eased considerably with use and became quite comfortable by day two. This did not happen with the 10x unit as it was comfortable straight out of the box. Talking of which, it also came with objective covers already fitted, and while I have never used these in the past, I was impressed by these. Whereas other objective covers I have experienced have been rather crude rubber flaps attached by simple rubber rings, these not only appear to actually be the work of a design studio (see pic) but, amazingly, also the work of the same design studio that styled these binoculars, the covers even having the Zeiss logo on the inside as well as the outside! I can’t believe I am suggesting that objective covers can be stylish, but it’s true. So I decided to leave them in place.

The question I was most keen to answer was, does this model share the bright, transparent colours that the 8x40 has?

The answer is yes. This model shares the same colour reproduction as the 8x model and very nice it is too. The position of the focus wheel allows three of your fingers to securely grip the tubes below the hinge, while your first finger then falls naturally on the focus wheel, without having to ‘reach’ or search for it, and this arrangement allowed me to hold this 10x model steadier than I anticipated.

We had many sightings of Otters in the bay overlooked by our rental cottage. Typically, they would dive and forage in the seaweed forests and return to the surface with food items, often crabs, but equally often, small items that they quickly ate and swallowed. We only saw one Otter at a time but on one occasion I could see the Otter had the narrow, pretty face of a female, while on another occasion the Otter had the broader, more ‘Churchillian’, face of a male, so our bay was being visited by at least two different Otters. The spasmodic appearance of Otters in the bay suggested to me that they were not resident here but visited from time to time.

On most days our bay was visited by large Atlantic Grey Seals. These are powerful animals, certainly the top predators here (unless a pod of Orcas wanders by) and the one that repeatedly visited us had characteristic brown blotches on its head. Usually, this individual moved around in a leisurely fashion but on one occasion it submerged and then suddenly surfaced some distance away, demonstrating the speed they have available when they choose to use it. By the way the SFLs imaged the Grey Seals’ whiskers very nicely, these binos are sharp! We were also visited occasionally by Common Seal, these being easily distinguishable by their size, colour and their faces having a prominent brow, unlike the Roman noses of the Grey Seals with a smooth curve from the top of their head to their nostrils.

Also regular visitors to the bay were several Great Northern Divers (Common Loons) sometimes as pairs swimming separately, which we took to be an adult and an immature, but also as single birds that were distinguishable from each other by the different extents of white on the head. A single sighting of a winter-plumage Red-throated Diver was nice, and out over the Atlantic there was the very occasional Gannet, too far away for the SFL’s 10x magnification to reveal the yellow on the head, but the shape, and those black wingtips are unmistakeable. From time to time, we could see straggling lines of Kittiwakes out over the Atlantic, again more by familiarity with their mode of flight than the perception of details although sometimes the sunlight was good enough to illuminate their black wingtips.

Along the edge of water there was always 2-3 Ringed Plovers, occasionally accompanied by a Sanderling or a small group of Redshanks, whose ‘Tyoo-to’ calls always remind us of our early visits to Walberswick in Suffolk where we first learned their calls. From time to time, small groups of Curlew flew overhead, as did a single Raven that seemed to comment on our presence with a deep ‘Kronk’ of disapproval. We particularly enjoyed seeing several Turnstones here too, this species being a favourite of ours, but regular searching of the rocks unfortunately failed to find any Purple Sandpipers which would have been the icing on the ‘wader-cake’ for us.

An unfamiliar white shape out on the open sea just outside the bay, was revealed by the SFLs to be a Black Guillemot in winter plumage. We have adopted the Shetland name for these birds: Tystie (which we pronounce as ‘tice-sti’) as we see this species most often when visiting Islay in the winter months and it seems logically clumsy to us to be calling a white bird a Black Guillemot, and Tystie, to us at least, sounds friendlier.

A dry-stone wall (i.e., a stone wall built without mortar) ran from our cottage a short distance down the slope of ‘our’ property and it provided a landing place and look-out for resident Wrens and Robins, as well as visiting Redwings, a Buzzard, Jackdaws and Choughs. The Redwings had much darker plumage than those we get back home, and one evening the Buzzard surprised us by perching there for over an hour at dusk. But the biggest surprise of all, since the nearest trees are about 2 miles away from our cottage, was the arrival on the wall of a Mistle Thrush. Known in some places as Stormcock from its determination to keep singing despite strong winds and driving rain, this beauty arrived with its head held high and a bold confidence that distinguished it from the rather nervous Redwings.

Overhead, we had a fly-by visit by a Sea Eagle, all big wings, and a heavy head/bill, and not much tail to speak of, and quite a different silhouette from the Golden Eagle that cruised nonchalantly-by a couple of days later. More constant visitors were the gulls of course, the occasional Black-headed, a constant stream of Common and Herring, in a variety of ages and plumages, and from time to time, a menacing Great Black-backed Gull. We didn’t see any Lesser Black-backed.

But best of all were the regular flocks of Barnacle Geese, one of which was certainly over 700 strong, passing low over our heads, their voices a constant loud hubbub of conversations, presumably of family groups ensuring they stay together. To see so many, so low overhead, and to hear their wings beating the air and their voices clamouring as they constantly sought to take advantage of the slipstream of the goose in front, creating those famous v-formations, was so awesome, it simply left us breathless and feeling quite emotional.

By contrast, the vocalisations of the local Choughs always left us smiling. Why? Well, although ‘Chough’ is usually (in England at least) pronounced ‘chuff’, from its spelling, my theory is that it was originally intended to rhyme with ‘plough’, and be pronounced ‘chow’, simply because this is the call this species makes: an utterly joyful, and even mischievous, ‘CHOW’! This was especially so when we startled a flock of around 30 Choughs on the dunes, and they took flight with a raucous chorus of CHOWs that had us both grinning. Through the SFLs their smart black plumage and red bills were simply stunning, and it was a delight to watch them forage on the ground, one moment carefully probing the turf and the next, bounding jauntily to investigate a new spot.

Down at ground level the SFLs displayed their versatility with a close focus distance of around 1.25m / 4ft and gave spectacular views of the huge variety of fungi here at this time of year. Why use binoculars to view these instead of kneeling down and using the Mk.1 eyeball? There are simply too many weird and wonderful fungi here to contemplate getting down then getting back up multiple times in less than half a dozen steps. Mindful of being on Birdforum and not ‘Fungiforum‘ I will just mention two varieties and post 2 photos below. One bunch looked like something straight out of a fairy tale, all red pixie-hoods, and the other looked like nothing more than a bunch of pasta sticks.

The colour of the sea in the bay we overlooked varied according to the seabed below. Over clear sand, the colour was a gorgeous turquoise, while over seaweed-beds it was nearly purple. These shades of colour changed in accordance with changes in the sunlight and sometimes the sea could appear simply grey. Whether these colour changes were subtle or dramatic, the SFLs tracked these faithfully and realistically, which added greatly to the realism of the image.
So, all in all, these 10x40 SFLs are very impressive performers and certainly achieve the high standards I expected following my review of the 8x40 model. Sharp, with great colours, and no distracting chromatic aberration in the main 80-85% of the field of view, and with a grip that aids the steadiness of the image, despite the 10x magnification and the brisk winds here on Islay that can both generate bino-shake.

My favourite magnification is still 8x, but these compact and lightweight binoculars make a strong case for 10x so if you are looking for 10x binoculars and have a budget of around £1600, I recommend you audition these.

Lee

Zeiss SFL 10x40: A Field Review (2024)
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