Kowa YF 30 Binoculars
binocular made especially for kids
compact high-performance porro prisms
field of view, great depth of field
Kowa released their YF binoculars in August of 2011, and there is a story behind these that we really love.
These binoculars were originally co-designed by an American and a Japanese engineer, both of whom had 4-year-old children.
As such, the YF30 binoculars are somewhat unusual in the optics market because they were designed and optimized just for kids.
Children will like the YF binoculars because they are compact and lightweight. They have a large focus knob that turns easily
and smoothly, and they were specifically made to fit smaller faces, though they will accommodate most adults as well. Parents
will like the YF binoculars because they are very affordable at just $100.00
for either the 6x or 8x model. In 2020, Kowa introduced the YF II binoculars which retained the original optics but changed the
cosmetics of the YF to match the same green as their other binoculars and spotting scopes. Let us tell you more about why we
really like these.
YF binoculars from Kowa are
a porro prism design, meaning that they are wider than they are tall.
These binoculars stand 4.5 inches tall and measure 6.25 inches across,
but fold down to just over 5 inches width. That means they have a very
broad interpupillary distance range (think of this as the distance between
your eyes) of 50-71 mm. Most roof prism binoculars have only 16-18 mm
of interpupillary distance range and they typically have a minimum of
55-58 mm. This means that the YF binoculars fit much more comfortably
on a small face, though they will also accommodate most adults. The YF
comes in 6x30 and 8x30 models, all in black rubber armoring with red accents.
The 6x and 8x refer to the magnification of the binocular, while the 30
is a reference to the diameter of the objective lenses in millimeters
which gives a rough estimate of how much light they can admit. Greater
width means more light, but at the cost of size and weight. Since the
goal was a compact, lightweight binocular for little hands to use, they
went with smaller objective lenses. It’s a good choice. The YFs are
feather-light, at 17.1 oz. for the 8x model and just 16.8 oz. for the
The focusing knob is particularly
large, and its rubber coating has cut-out ovals that provide additional
purchase, making it easier for small fingers to use. The action is very
smooth which again makes it easier for a younger user to manipulate it.
The focus mechanism is pitched quite steeply: these binoculars go from
minimum close focus to infinity in about 0.7 turns of the knob. Having
less distance to travel to achieve reasonable focus is an advantage in
a child’s hands. The published minimum close focus for the YF binoculars
is 16.5 feet, but when we tested it, we found they were quite a bit better
in practice. We measured both models of Yfs at 13 feet. That distance
will vary from user to user, but they are good estimates. And while a
minimum close focus of around 10 feet is not particularly close by modern
binocular standards, the YFs have excellent depth of field. This means
that when they are focused to a particular point, the amount of the world
behind and in front of the point that is still in focus is greater on
the YFs than on an average binocular, a property that is of great benefit
to a child whose precision in focusing may not be as good as an adult’s.
Interestingly, the two models have rather different eye relief at 20 mm
for the 6x30 and 16 mm for the 8x30. Eye relief in the 16-20 mm range
is generally sufficient for all users.
We found the Kowa YF binoculars
to be surprisingly bright for a 30-mm binocular. The image quality was
excellent, very sharp and vibrant. Color fidelity was great with no detectable
bias in color; brilliant white objects stayed brilliant white. The YF
binoculars also did well in terms of having very little chromatic aberration
– that fringe of color that is visible on the edges of very brightly-lit
objects, and that was mostly at the outer portion of the visual field.
There was almost no “pin-cushioning” – the tendency for straight
lines to bow inward at the edge of the visual field. Those observations
suggest that the Kowas have really good flat-field performance. Balanced
against this, we noted that the edges of the field were a bit “mushy”,
focally. This is less important since, of course, you look through the
center of the lens and not the edge. One property at which the Kowa FY
binoculars excel is the size of the field of view. The 6x30 YF binoculars
have a 420-foot field of view at 1000 yards. The 8x30 being higher magnification
have a smaller field of view than their cousins, but it’s still a very
hefty 393 feet at 1000 yards. This property has important consequences,
especially for someone inexperienced with binoculars trying to aim them
at something. First, if you can see more of the world around you at a
glance, the chances are better that what you were looking for specifically
is in view when you lift the binocular. It’s worth noting in this context
that lower magnification is also advantageous when little hands may not
hold a binocular as steady, since image shake is reduced at lower magnification.
The 30-mm barrels are also easier for a child to hold steady. Kowa binoculars
are made with high-quality BaK-4 glass prisms and are fully multi-coated
for increased light transmission and brighter images.
In the key user-adjustable
parameters, everything is simple and basic on the YF binoculars. The diopter
is adjusted with a twist ring on the right ocular. A raised ridge on the
ring lines up with a white dot on the ocular tube to indicate the position
for equal eyes, while plus and minus signs to either side indicate the
direction of adjustment. The ring stiffly resists movement to help hold
its place. The eyecups adjust with a helical twist: counter –clockwise
pulls the cup out while clockwise closes it down. There are two completely
stable eyecup positions between fully in and fully out, marked by solid
detents. There’s nothing fancy here, but it is all functional and utilitarian.
Kowa did really well with these properties.
Traditionally porro-prism binoculars
aren’t sealed, so most are not waterproof, but the Kowa YFs are sealed
and waterproof at least initially. We have no data about how long they
retain that status with use and wear. It is worth noting in this context
that Kowa warrants their product to be free of defects in material and
workmanship for the lifetime of the product. The rain guard is the same
kind that we’ve seen again and again: a pair of soft rubber cups joined
by a flexible bridge region. The strap threads through a complete bracket
on the left side and a gapped one on the right, so that it can be readily
detached and swung free if the user prefers that. The fit of the rainguard
is tight enough that it is not readily dislodged even when inverted and
shaken, but it goes on easily. In other words, it’s about perfect. The
hard plastic objective lens caps don’t fit as securely. In fact, these
will dislodge easily and be lost in the field, so their primary function
is to protect the lenses when putting the binocular in its case. Had they
been made out of the same rubber used in the rain guard, they might have
been a bit more useful, but overall, it’s a very minor point. The strap
is the usual inch-wide, padded leather and nylon cord affair. The strap
fits into recessed lugs at the corners of the objective tubes where they
won’t come into contact with the hands, a nice bit of design. In a binocular
this light, the strap has little impact on user comfort, and if it’s
an issue, there are plenty of comfortable straps and harnesses available.
The rubber armoring is comfortable in the hands, providing a secure grip
without adding too much weight, a nice compromise overall. Lastly, the
case is a simple padded vinyl affair with enough room to easily house
the optic, and a flap with a Velcro closure that adequately covers the
binocular. The case has a belt loop on the back, to facilitate carrying
it into the field.
While it’s clear that the
Kowa YF binoculars were made with kids in mind, kids may not be the only
users who will like it. Due to the compact, supremely lightweight design,
the surprisingly good optical performance and the very low price gives
the YFs a broader appeal than they might otherwise have. This is a great
first binocular for a beginning birder of any age. By the way, all the
features that make them ideal for kids or beginners also make them a great
binocular for more elderly users. We wish we’d had starter binoculars
this good when we first began looking at birds!
YF 30 Binoculars