Nikon have produced some of the best
porro-prism binoculars ever. These Nikon Marine 7x50s are made in Japan, just
like their famous Superior E range, but do they give a similarly superior view?
Nikon
Marine 7x50 IF WP Review
Nikon’s Marine 7x50s are a rare thing these days – a
Japanese-made porro-prism binocular. Their spec’s are superficially similar to Nikon’s premium
Prostar 7x50s, but they’re very different in reality. So
are these some kind of sibling to Nikon’s outstanding Superior E line of
porro-prism binoculars? Maybe a rubber-coated big brother to the 10x35 EII?
Let’s find out …
At A
Glance
|
Magnification |
7x |
|
Objective Size |
50mm |
|
Eye Relief |
18mm claimed (12mm actual) |
|
Actual Field of View |
7.5 degrees |
|
Apparent field of view |
49.3 degrees |
|
Close focus |
25m |
|
Transmissivity |
95% |
|
Length |
181mm |
|
Weight |
1170g |
Data from Nikon Europe.
Design
and Build
Any idea that these are basically the same binocular as the
Prostar 7x50 IF SP WP disappears as soon as you put them alongside: the
Prostars are much bigger in every dimension and quite different externally; I
can’t find a single common component. The 7x50 Tropical IF HP WP is undoubtedly similar to the Prostars; these
Marines are not.
Even more confusingly, Nikon also seem to sell a central-focus
Chinese-made Marine CF WP 7x50 model. I’ve said it before - Nikon, like Playboy,
have more models than they should.
And what about all those two-letter abbreviations: IF? WP? IF-
Individual Focusing. WP – Waterproof.
Body and Ergonomics
Compared to the Prostars, these look... not exactly cheap,
just ordinary, and are covered in thin black rubber armour that looks just like
that on a Minox. They don’t have that Prostar look of
a piece of Navy equipment, or the fabulous level of engineering.
Nikon claim waterproofing for these, hence the name, but it’s
to just 2m for 5 minutes – a lower level than the Prostars or Tropicals.
Internally the Marines also look well-made and of similar
design to the Prostars, but the components are again all quite different.
Not only are they smaller than the premium Nikon 7x50 models,
but the Marines are lighter as well, at 1170g.
The hinge is just Marked “AO Japan”, suggesting these might be a re-badged generic model, or
at least outsourced (to Asahi Optical?). Confusingly, though, the prism housing
bears the Circle-C ‘Criterion’ mark that once meant good things on a pair of Nikon 8x30 (or 10x35) Es, but that has generally fallen out
of use.
Made in Japan,
but maybe not by Nikon.
Focuser
Like the Prostars and Tropics, the Marines have individual eyepiece focusing, which may be fine for scanning the horizon from the bridge of a yacht; or indeed for astronomy. But otherwise, it’s honestly a pain.
Individual
ocular focusing. Deeply recessed eye lenses mean real eye relief is much less
than claimed.
Optics - Prisms
These are a
completely conventional porro-prism design.
Optics - Objectives
The
objectives are much less deeply recessed than the Prostars’ and are held in by
a single lock-ring.
They are
properly multi-coated, but again the coatings aren’t quite up to the premium
standard of the Prostars’. Nonetheless, Nikon claim 95% transmission, which is
a very high level for any binocular: it that why they bear the ‘Criterion’ hallmark?
Full multi
coatings are not quite as good as the Prostars’.
Optics - Eyepieces
The
eyepieces are rubber covered and have a printed rather than engraved scale like
the Prostars’. Flat eye lenses sit below thin, folding eye cups.
Next to the
left ocular these are marked “7x50 7.5° WP ©”, so in theory they have a
slightly wider field than the Prostars’.
Nikon
actually claim larger eye relief for the Marines (at 18mm) than the Prostars
(16mm), but in fact I measured just 12mm from the eyecup for the Marines, so
the 18mm must be measured from the lens. This is borne out in use. Make no mistake, these have less ER than the
Prostars, no matter what the brochure says.
Accessories
Included are
a fairly low-rent cordura case, stay on objective
covers and a thin plastic strap.
Straps and
case are cheap, generic items. Prostars have leather.
In Use –
Daytime
Ergonomics and Handling
Handling is
typical for a large porro-prism binocular. The Marines are heavy, but not
unduly so. Individual ocular focusing is inconvenient for terrestrial use, much
less so for astronomy and marine, where they tend to stay focused on infinity.
The View
The centre
field is reasonably sharp and detailed, with decent colour rendition and good
brightness. However, these are very hard to focus because the focus point is
very indistinct, a sure sign of not-so-good optics. The main problem, though is
extreme field curvature.
Overall the Marines are not a pleasant binocular to use in the daytime, due only
to that very curved field, small sweet-spot and vague focusing.
Flat field?
These binoculars have terrible field
curvature off axis, from only ~45% of the field width, so that theoretically-wider
field in fact turns into a miniscule usable sharp area.
The
field-curvature problem is exactly the same in both barrels and is not a fault
– they were designed this way. The question is, why? Could it be that Nikon are
assuming that centre field is all-important for marine use? That the grey
expanse of waves on either side of the distant ship doesn’t matter much? Not
unreasonable, I suppose, but it spoils the view for use on terra firma.
Chromatic Aberration
The Marines
are sharp and CA-free on axis, typical of good external-focusing bino’s. But
that’s the end of the good news. Off-axis, false colour increases a lot, just
like every other aberration you can think of.
In Use –
Dusk
The
high-transmission optics and big objectives mean these perform well into dusk.
In Use – Observing
the Night Sky
Surprisingly,
once you get them focused (not easy with a vague sweet spot and individual
focusing), the Marines work well for astronomy. Nikon claim a very high light
throughput of 95% for the Marines and they certainly seem every bit as bright
as the Prostars (but bear in mind that my exit pupils only go to about 6mm, not
the full 7mm).
The heavy
off-axis aberrations create a tunnel-like effect on the night sky, but I could
learn to ignore it.
The Moon
The Moon
looks decent, with minimal chromatic aberration. Little flare or ghosting is
visible with the Moon in-field. With the Moon just outside the field there is
some veiling flare and reflections off the side of the tube, but no more than
is normal with mid-range bino’s.
Jupiter
Jupiter
shows the moons easily as perfect points and the Jovian disk shows only a
little spiking and flare (but more than the Prostars and other premium
binoculars).
Deep Sky
Stellar
images are not as tight as the Prostars’, but quite acceptable nonetheless.
Star fields are nice and star-colours good: Albireo is easily split and an
enjoyable sight with these. Enough of the field is visible and flat to take in
most objects and the good light throughput means that these go deep and diffuse
DSOs, like M33, are easy to find.
Perhaps at night it’s easier to ignore
the off-axis aberrations, but I found the Marines quite usable for astronomy.
Nikon
Marine 7x50 IF WP vs Nikon Prostar 7x50 IF SP WP
These
binoculars share similar numbers, but not much else. To clarify that, here’s a
quick synopsis of their differences:
·
The
Prostars are a superbly made, heavy duty binocular. The Marines are just an
ordinary mid-range model
·
The
Prostars are much bigger and heavier and look totally different with
leatherette vs the Marines’ rubber armour
·
The
Prostars have a flat field; the Marines’ is horribly curved
·
The
Prostars have sensible eye relief, the Marines too little (whatever the
brochure says)
·
Both
have individual ocular focusing
·
Both
are waterproof (though the Marines less so)
Summary
The Marines
are interesting because they make a point about binocular design. They are an
unpleasant binocular for terrestrial use with way too much off-axis field
curvature and astigmatism. But they still have modern glass and multi-coatings.
This means that in the dusk and at night they will outperform even a
super-premium 1970s binocular (a Zeiss Oberkochen
perhaps), just because they let more light through, more
light in fact than almost any roof-prism binocular.
In fact,
these Marine 7x50s are also quite sharp on-axis.
So they work rather well for astronomy, as long as you
concentrate on the centre of the field, where stars are tight and bright, and
ignore the time-warp tunnel effect from the off-axis curvature and astigmatism.
Should you
buy them? Only if they are cheap as the proverbial, in which case they might
make a good binocular to leave on your canal boat, your cabin cruiser, or
perhaps in your observatory.
I habitually
used to leave an old-but-good pair of Japanese 7x50s on the floor of my
observatory for bored moments taking subs for imaging. Then the water main
burst and flooded my dome, ruining the binoculars. These Marines would have doubtless
have survived.
Not recommended except
for astronomers looking for a ‘leave them in the observatory’ pair, or perhaps for
their intended purpose on the bridge of a boat.