Zeiss SFL 8x30 Binoculars
- Small Size
- Focus Knob Placement
In 2022, Zeiss released their SFL (SmartFocus Lightweight) binocular line with 8x40 and 10x40 models. This was a fairly high-performance optics
line, and it was priced accordingly at $1,799.99. The 40 mm objective lens
size put those binoculars in the “full-size” category. The following year, Zeiss announced two more models in the SFL line, the 8x30 and 10x30
versions. So, when we got a demo copy of the 8x30 model, we were excited to field test a high-end “mid-size” roof prism binocular. The 30 mm
SFLs are less costly than their larger brethren by a fair bit, being priced at $1,499.99.
We don’t usually begin a review discussing pricing in the first paragraph. But in this case, it’s a reasonable starting point, given what this
product is, and what it isn’t. Available statistics say first-time buyers are less likely to spend $1,499.99
on their first binocular. In our view, mid-size binoculars are decidedly a niche market. It’s not that there aren’t plenty of models from lots
of manufacturers to choose from; it’s because there are very few really good ones. Why is that? Well, a 30 mm objective lens physically limits
how much light gets through to the eye, relative to a 42 mm lens. This means that to deliver satisfying optical performance in a mid-size binocular,
manufacturers must use really good glass and coatings to maximize light throughput, and that drives the price up. So, retreating from those optical
woods for a minute, the market for a high-end, mid-size binocular like the 8x30 SFL is fairly small. There are two major advantages to a premium quality,
mid-size binocular: smaller size and lighter weight. And make no mistake about it, despite their small size, these beauties from Zeiss really deliver that
optical performance that deserves the label of premium quality!
Reviewing a product like the Zeiss SFL 8x30 binoculars is a fun job! The image quality is superb: bright, tack sharp and free of any detectable color bias.
Mid-size binoculars usually have a large field of view relative to a full-sized binoculars. Even given that, the SFL 8x30 binocular has a notably large
field of view: 426-feet at 1000 yards. We also observed that the image sharpness was maintained right out to the very edge of the visual field. This means
that the 30 mm SFLs have very little field curvature, which in turn means that more of that big field of view is of high image quality. Zeiss uses field
flattener lenses in the eyepieces to maximize sharpness and minimize distortion all the way to the edge of the image.
We measured the close focus at 4.5 feet. That’s simply outstanding performance for this trait. The focus knob is large, with ridges on the rubber coating
to improve traction. For people with larger hands, it may be more comfortable to focus with your middle finger rather than the index finger. Focusing was
smooth and relatively easy, even brand new out of the box. Getting from close focus to infinity requires about 1.4 turns of the knob, which is just about
right. This is what puts the “SF” (SmartFocus) in “SFL”; nature observers need particularly fast focus speeds to maintain a clear view of fast-moving
subjects like birds and insects. It is clear that Zeiss designed this binocular with nature observers in mind, and it makes a world of difference.
Depth of field is one of those properties that’s really hard to assess, given that it varies with the distance of the object being viewed, and it’s a
unit-less quality that can’t be measured directly. In practice, all you can do is compare the binocular in question with other optics in its class and
see how it does. We had one other 8x30 optic available to us, and SFLs exceeded its depth of field by a lot, so take that for what it’s worth. It also
exceeded that competitor in terms of brightness, by a shocking margin, by the way! We can thank Zeiss’s T* multi-layer lens coating for this, as its
job is to maximize light transmission. To maximize it further, the SFLs feature phase-coated BaK-4 prisms. These coatings also give the binocular
fantastic color fidelity.
Chromatic aberration is another of those unit-less attributes that cannot be directly measured. But in this case, since it’s a function of glass quality
and not a physical property, we had a lot more comparators available to us. On careful assessment, we felt that the chromatic aberration in the Zeiss
mid-size SFLs was fairly average, neither severely bad, nor incredibly good. To control chromatic aberration, Zeiss developed a UHD (Ultra-High-Definition)
lens system that made its debut in the larger SFL 40 mm line. This lens system is a step up from their HD system used in their Conquest HD Binoculars, but
certainly a step down from their Victory SF Binoculars that use their highest quality Ultra-FL (Fluoride) lenses. In essence, you get what you pay for, and
we think Zeiss correctly distinguishes these three tiers of lens systems.
The good news is that typically, chromatic aberration (unless it’s really bad) is usually worse at the field edges, and since the 8x30 SFLs have such a
large field, you’re not going to notice that chromatic aberration in the middle of that field. The Zeiss SFL 8x30s have the diopter adjustment under the
right ocular lens. It’s just a twist knob that has deliberately stiff resistance against movement in either direction. There is no scale that tells you
how much you’ve moved it, though the plus and minus directions are indicated on the knob.
The chassis is sealed, completely waterproof and nitrogen purged. That is all fairly standard on any high-end optic, but it’s good to know that everything
is as you expect it to be. These little binoculars are a bit over 4.7 inches long (12 cm) with the eyecups fully folded down, and about 5.1 inches (13 cm)
with them fully extended. They are about 4.5 inches wide (11.5 cm) with the hinge completely open. They have an interpupilary distance range of 54-74 mm,
which is broad enough to work with most people’s faces, especially those with closely set eyes. They weigh 16.4 ounces with the rainguard and objective
lens covers included. That’s feather-light! These binoculars are coated in thick rubber armoring, which protects them if they get knocked around a bit.
The armoring is smooth but has a pleasantly “sticky” feel to it, almost as though they are adhering to your hands, except they aren’t! There are ridges
in the armoring at exactly the point where your fingers meet your palm, which helps increase the security of the grip. The eyecups extend with a helical
twist mechanism, with two stable detents between fully in and out. We had no problems with the eyecups collapsing inadvertently during field testing. The
only issue this reviewer had was that the extension of the eyecups was not quite enough to prevent the visual field from blacking out periodically. It’s
worth noting that this reviewer also requires more eye relief than anyone else at Optics4Birding, so maybe this isn’t a huge problem, but it may be
something that other users experience as well.
Focusing on these 32-mm Victory SFs is really smooth right out of the box. Testing indicated that going from minimum close focus to infinity takes about 1.6 turns
of the focus knob, which is pretty much perfect. This allows for precision focusing of the binocular without taking too long to get there. The focus knob rubber is
soft and pliable, and the knob is covered in broad ridges that impart a secure grip even when wet. Zeiss lists the minimum close focus distance at 6 feet
(about 2 meters) for the 8x 32 Victory SF binocular. This characteristic can vary somewhat with the user, and we found at least one person who tested out at just 5.5
feet for minimum close focus. Either way, that’s great performance on this characteristic.
In summary, we enjoyed field testing the Zeiss 8x30 SFL binoculars. Their compact size and light weight made them very comfortable to travel with and carry
in the field. The image quality was excellent, the ergonomics well designed, and the field of view so large that we basically missed nothing in the field
under normal conditions. This is a binocular that we would enjoy owning ourselves, which is saying a lot! One of Zeiss’s stated missions with these
binoculars is to give outdoor enthusiasts a binocular that lets them focus on the scenery rather than their equipment. With such a quick focus mechanism
and a feather-light design that does not compromise on image quality, we think Zeiss accomplished that mission wonderfully.
To purchase or compare any or all of the Zeiss SFL models click here.