Review of Zeiss 10 x 40 SFL binocular
First things first. I must admit that I’m a confirmed addict of the Zeiss Victory SF’s. I love pretty much everything about them and consider them the pinnacle of birding binoculars. I was therefore initially wary of reviewing the new SFL’s, as once you are used to the best, what can you say about the rest? I was wrong.
Straight from the box, I was immediately in familiar territory. While the 10×40 SFL (SmartFocus Lightweight) are obviously smaller and lack the third bridge that is so distinctive of many modern roof prism bins, the black rubber armouring, focus wheel and the overall ergonomics all looked reassuringly familiar. On picking them up, the weight, or rather the lack of weight, was also immediately apparent. They have a magnesium body and slimmed down lenses that cut the weight to 640g. That’s a full 150g lighter than the Victory SF and around 200g lighter than equivalent magnification Swarovski models. This is a considerable amount and a big consideration for anyone who will be spending long days in the field, as well as those who will be doing a lot of travelling. The SFL’s also come with the usual ergonomic Zeiss branded Air Cell Comfort strap, attached via solid metal lugs. The rubber eyecups have three clicks to full extension, giving a range of eye relief to suit everyone, and the objective lenses have optional lens caps that can be fitted very snugly over the ends of the barrels. These are also ergonomic and shaped to fit the left and right barrels (look for the discrete L and R printed on the caps).
Once out birding, these SFL’s really do shine. They feel very natural to hold. On lifting them to my eyes, my index and middle fingers immediately fell into place on the focus wheel, meaning no awkward finger ballet is necessary. I then performed the balance test. What I call the balance test is simply holding the bins up to your eyes normally, then removing all of your fingers from gripping the bins so that they are left balancing on your thumbs. This means that the weight distribution of the bins is pretty much perfect, making prolonged viewing much more comfortable. In fact, I would go so far as to say I would not even consider owning binoculars that did not pass this test nowadays. Once you have used perfectly balanced binoculars, picking up other models feels like handling a brick. The focus wheel itself is a nice size (there should be no issues using it with gloves), but crucially the focus mechanism is just a dream to use. The wheel moves smoothly back and forth through the complete revolution and does not feel gritty, clunky or loose in the slightest. Just a smooth, oily motion that has the tiniest bit of initial resistance and then off it goes. Smooth as silk. So many modern binoculars have achieved wonders with optics but criminally neglected their focus mechanisms, and I’ll never understand why. We use the focus wheel constantly, and Zeiss clearly recognise this and have achieved what so many others cannot; a smooth focus.
While I’m on the subject of focus, the SFL’s boast a very similar feature to the flagship SF’s. Namely the amount of turning required to focus. I reckon most of my birding is between the 10m-infinity range. Going from 10m to infinity with the SFL’s requires just 1/8 of a turn of the wheel. When getting onto birds quickly and accurately can make all the difference, this precision and depth of field is a joy to behold, and it just contributes to the overall quality feel, handling and most importantly, the long-term useability of these binoculars.
Now for the optics. Undoubtedly the most important part of any binocular is its optics. The SFL’s feature the Zeiss Ultra-High-Definition concept of coatings and lens design, plus Zeiss T* Coating on its lenses, as well as the LotuTec coating on the outer lenses to reduce moisture build up in wet weather. This all adds up to achieve an incredibly sharp, bright and naturally coloured image that I really was not expecting to be as good as it is. Edges and veins of leaves are razor sharp, and colours are true to life. The image is sharp to the edge of the field of view, and I could not detect any chromatic aberration. The field of view is stated to be 115m at 1000m range, and scanning produces no annoying “barrelling” effects. Just a smooth natural view, as it should be. Using them in a variety of April lights, I was impressed that they could pull out colour details on ducks that were against strong light and could easily pick out plumage patterns on Goldfinches high up against the light sky at dawn at 125m range. Close focussing is about 1.5m, making these a real option for those interested in viewing insects.
Their performance in twilight was also impressive. With 90% light transmission, this is to be expected, but it was still pleasing to see the same pink apple blossom and timber detail on my shed revealed by the SFL’s over 50 minutes after sunset and under thick cloud conditions as was also achieved by my SF’s.
They are nitrogen filled and waterproof.
Overall, I have to say I am impressed. These will retail around or under the £1,600 mark, and as such shave a considerable margin off the top end binoculars without really compromising on optical quality. Indeed, many people will find the reduced weight and dimensions preferable. The specs are all superior to their roughly equivalent-priced competitors, making these well worthy of consideration when you’re next in the market for new bins.
Paul French
