buying binoculars - Bird Watching Magazine

buying binoculars - Bird Watching Magazine
BEGINNERS GUIDE TO
BUYING BINOCULARS
Your quick guide to the anatomy of a birdwatchers’ best friend
There’s a bewildering array of binoculars on the market these
days, but the good news is that even many of the cheapest
models are now capable of great performance. So what
should you be looking for when you buy? Our quick guide
to buying binoculars tells you what to look for when you test
a prospective purchase (always try the actual pair, not just
the model, that you’re planning to buy), and what some of
the jargon used to describe binoculars means. And always
remember, it’s about what suits you – everybody’s eyes are
different, so don’t just rely on the technical specifications.
COMFORT
No matter how good the optics,
you need binoculars you feel
comfortable using for extended
periods. Check the eyecups are
comfortable, the barrels and focus
wheel are easy to grip, that they’re
not too heavy to hold steady or
carry for long periods, and that
they hang flat against your body.
FOCUSING
Check that the focus wheel travels
smoothly, as well as how stiffly it travels
and how many turns it takes from close
focus to infinity – in the field, you’ll want
to be able to find focus quickly.
OBJECTIVE LENSES
The bigger these are, the brighter
the image produced. Their
diameter, in millimetres, is stated in
the binoculars’ designation; for
example, 8x42 binoculars have
42mm objective lenses.
DIOPTRE ADJUSTMENT
Located on the focus wheel or one
of the barrels, this compensates for
differences between your two eyes,
check it sets easily, and crucially
that it will stay in place while in use.
POWER
Binocular
designations’ initial
figures describe
the magnification
provided by the
prisms in the
barrels; 8x42
binoculars, then,
magnify images by 8
times. The higher it
is, though, the
narrower the view,
and the more any
movement of the
bins will be
noticed.
EYECUPS
OPEN & CLOSED BRIDGE DESIGNS
Open-bridge designs (such as the binoculars on the
immediate right in this panel) can be easier to grip and handle
securely, and may also be lighter, although other factors such
as the size and quality of lenses also comes into play here.
The familiar closed-bridge design (far right), may suit many
users better, though, depending on hand size.
Nearly all, these days, twist up to
several positions to suit all users –
the quoted ‘eye relief’ figure is how
far out they’ll twist. Glasses wearers
will need them pushed fully down.
Check that they stay in position
while in use.
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