Minox 15x58
FL Review
Fluorite can
be an emotive thing in this hobby, which is why you see it used in so much
advertising. The time I first came across the big Minox
binoculars I was the proud owner of two refractors containing fluorite in their
objectives: an FS128 and an FS102. I liked both scopes a great deal, so the
idea of a high-power binocular containing the magic mineral appealed.
At that time
I had just been getting interested in binocular astronomy beyond casual
sweeping and looking at the Moon and the brightest Messier objects. I had
realised that I needed more power and bigger objectives to go deeper, but I
didn’t want big binos I would have to mount on a tripod:
to me the immediacy of hand-held binoculars is what makes them different from
dragging out a telescope or opening the dome.
In my
opinion 15x magnification is about the very most you can hand-hold without a
tripod or image stabilisation. There are very few quality hand-held binoculars
made with a 15x magnification, because it is a design that appeals mainly to
highly specialised niche markets, like hunters, plane spotters and astronomers.
Apart from the Minox, there is a Swarovski 15x56, a
Leica 10+15x50 dual-power, both reviewed elsewhere on this site, and that’s
about it. Other high-power binoculars tend to be much bigger and not really holdable, or of dubious quality. And of course, being
essentially a hunting binocular, the Minox are fully
waterproof unlike most big porros.
“But I don’t
need waterproof binoculars for astronomy!” you say. Are you sure? One of the
things a completely sealed binocular does is to prevent internal fogging during
prolonged use in extreme cold, something which could be useful in an astro’ bino’. Then again, I
sometimes take binoculars with me to the top of the local fell where there are
great views of the Moon and inner planets when low in the sky. On my hour-long
trip up the fell, sudden and heavy showers are not exactly unknown. So
certainly for me, waterproofing is a nice-to-have, if not absolutely necessary.
The Minox 15x58s are no longer made and even when I bought mine
a few years back they were being heavily discounted; nobody wanted them it
seems. Mine came ex-display from a dear-stalking outfitters in the Scottish
Highlands. I imagined them having sat gathering dust amidst kilts and antlers
and bars of Kendal mint cake, whilst the mists rolled past the window in some
sleepy Glen. I probably wasn’t far off, because when they arrived, the
eyepieces were coated in a film of impacted dust and grime (which was easily
removed): they must have been on display for years.
Design and
Build
Body and ergonomics
Look and
feel of the Minox is distinctly mid-range and
Japanese, not premium and German.
The 15x58s
are large for a roof prism binocular, arrestingly large and very long in the
barrel, so that they look vaguely menacing. They weigh almost 1.5 kg. If you go
for a walk with these on a Sunday afternoon, forget blending in with the bino-toting crowds; you won’t, because these look massive
and ridiculous hanging around your neck.
First
impressions are that they don’t have the elegance of a Leica and the build
quality doesn’t feel in the alpha class either, though perfectly acceptable.
The black armour looks more like the covering it is, than an integral part of
the body the way it does with the best. Plastic parts like the focuser and the
eye cups are more... well plasticky than they would be on a Leica. So these are not an
especially attractive pair of binoculars. That said, they are clearly well
built as they have waterproofness specs equal to the very best and instead of
nitrogen purging you get argon
purging (argon, being an inert gas, should help prevent internal corrosion).
The lens coatings look good too and behind those big lenses (it’s amazing, by
the way, how much bigger 58mm looks than 50mm) are a series of ridged baffles
machined in to the barrel.
Optics
Of the three
58mm models Minox used to sell, only the 10x and 15x
claimed use of Fluorite. I now know that when manufacturers say “Fluorite”,
what they often mean is “high fluoride glass”. Does this small deception
matter? I believe so, because Fluorite certainly isn’t a glass, it’s a
crystalline material; also, fluorite allows a level of correction for chromatic
aberration that even high-fluoride glass like FPL53 can’t quite match. Anyway, I have no idea if the Minox
contain fluorite or not; finding out involves using a laser (glass scatters the
beam and you can see it in the glass, Fluorite doesn’t and you can’t). What is
crucial is that in either case, you could expect that these binoculars would be
very well corrected for chromatic aberration.
The blurb on
the big Minox say that they use aspherical
elements in the eye lenses and they contain fewer elements than some premium binos. Even so, they manage a decent field of 4.1 degrees
and good eye relief; a flat field is claimed as well. The eyepieces have
twist-up eyecups and the right one also has the diopter
adjustment on my (early) pair, but later ones integrate it with the central
focus knob.
I should say
that the Minox looked very similar in some ways to
the Nikon Monarchs of the time and I suspect they may have been made under
license in the same Japanese factory, despite being a German brand.
In Use -
Daytime
Like many
high power binos, the Minox
are unimpressive under normal daytime conditions: relatively dim, with a narrow
field. More troubling is that focusing is rather soft and it’s hard to find the
best focus point. To make things worse, the right barrel seems a bit softer
than the left as well and is particularly difficult to focus. If that weren’t
disappointing enough, the fluorite (or FL glass) does little extra to control
chromatic aberration, which is at the level you tend to find in ordinary
binoculars, i.e. quite noticeable in high-contrast situations.
Dim, you
ask? How can they be dim with 58mm lenses? Here we need to delve into a bit of
theory. During daytime, your pupil contracts to just a millimetre or two in
size. This effectively stops down any binocular you use so that you are really
using 15x30s or whatever. How bright the binos seem
under daytime conditions has more to do with the transmissiveness
of the lenses and prisms than the objective size. So the Minox
probably seemed dim due to relatively ordinary coatings and prism mirrors. So
does this mean they are dim at night? No, because then your pupil dilates and
you get the full benefit of the big lenses.
In Use – The
Night Sky
The Minox were so lacklustre during the day that it was ages
before I ventured under the night sky with them. When I did I was mightily
surprised. Yes, they are heavy. No, the Moon isn’t as sharp and vivid as in a
premium binocular. However, deep sky objects with these are the best I have
seen with hand-held binoculars. Finding the Ring Nebula, the Crab and just
about any bright globular cluster is easy, as are many of the brighter
galaxies. You can see the dumbbell shape of the dumbbell, rather than just a
faint fuzz. What with the big objectives and comfortable view, the Minox prove a pleasure to use hunting Messier objects and I
have found things with them I haven’t with binos
before or since.
Why are
these binoculars so good on DSOs? Again, it’s all down to the maths. Light
gathering power is proportional to the area of a lens, so 58mm binoculars
gather 35% more light than 50mm ones. That’s a very strong argument, which
overwhelms any losses from slightly poorer coatings. The Minox
worked so well because they were big and had sensibly designed eyepieces,
that’s all. And for deep-sky, indifferent cornering doesn’t matter as much as
sheer horsepower, if you get the analogy.
From a
technical perspective the binoculars perform very well, too. The field is flat
as promised and eye relief is excellent. The field is narrow compared to lower
power binoculars, but is acceptable at 4.1 degrees and you can easily see the
field stop with glasses. These characteristics all sum up to make the view just
plain comfortable, as I said before. Ghosting is well controlled if a bright
light is placed just outside the field, so the baffling works. The full Moon
looks clean, with minimal flare, indicating good coatings and quality glass.
So these binos are great for Messier marathons, but they easily let
you keep track of the Galilean moons of Jupiter too and whilst our own Moon
isn’t as crisp as in a premium binocular, the high magnification shows a lot of
detail that lower powers don’t. Overall, then, night-sky performance is
excellent, belying the unimpressive daytime view. Interestingly, using them for
long distance viewing of ships in the bay in deep dusk conditions also plays to
their strengths, as you might expect.
The biggest
drawback for me with these monster binoculars is a combination of weight and
shakes. The only way I found to get them under control is to hold them around
the barrels, just behind the objectives, resting the eyepieces on my glasses;
mostly it’s worth the effort. In fact my observing pal likes them better than
any other binocular he has used. I find that I can only hold them for quite
short periods, but during those periods, deep sky performance is amazing for a
hand-held binocular.
Summary
In the end I
sold the big Minox binoculars. I am fussy and don’t
like mediocre optics and these were well short of perfect, particularly in the
right barrel. They didn’t have any better correction for CA than any other
binoculars either, despite the “fluorite” tag. All this meant nothing under the
night sky, though, because you could just see so much more with these than even
with, for example, Nikon’s 12x50 SEs. The main other problem for me was their
weight and bulk. Yet, they were smaller and wider of field than most “astro” binos. Even the 15x50
Leica Duovids didn’t measure up on deep sky, despite
having far superior optics in terms of clarity, sharpness and contrast. For
deep sky, aperture wins, even in hand-held binoculars.
If you ever stumble
across a pair for a sensible price, the big Minox
15x58s are cautiously recommended.
You can buy
Minox's updated 15x56 binoculars here: