MOUNTING PLATE
The Nikon 18-55mm and
18-105mm ‘kit’ lenses have
plastic mounting plates. All
other lenses in the group
have sturdier metal plates.FOCUS RING
This enables manual focusing or
full-time override of ring-type
ultrasonic autofocus. The
a m o u n t of rot a ti o n i n th e s e
lenses is typically quite small.ZOOM RANGE
Bigger often seems like better
when it comes to zoom range,
but there may be some loss of
image quality as a result.APERTURE
Wider apertures enable a tighter
depth of field and faster shutter
speeds, while constant apertures
mean you don’t need to tweak
your settings as you zoom.AUTOFOCUS
Lenses in this group feature
one of three different types of
autofocus system – a standard
electric motor, an ultrasonic
motor or, best of all, a ring-type
ultrasonic motor (see below).OPTICAL
STABILISATION
This can be a real bonus for
handheld shooting, especially
in low light. It usually gives an
advantage that’s equivalent to
nearly four stops of exposure,
enabling you to shoot handheld
at, say, 1/2 sec at 18mm, and
still get sharp shots.sharpness and smaller amounts
of image-spoiling colour
fringing and distortion.
Standard zooms don’t come
much smaller or lighter than
Nikon’s 18-55mm VR II, which
is often supplied as a ‘kit’ lens
with entry-level and mid-range
DX-format camera bodies. It
has a retractable design that
makes it remarkably small for
compact stowage. Moving up
the price ladder, the Nikon
18 -105m m V R i s a bigger len s
that dramatically increases
the zoom range. Again, it’s
available as a kit lens, this time
on more upmarket DX bodies.Constant-aperture options
T he ne x t step up i n budget
takes you to two Sigma lenses.
One is a 17-50mm that, unlike
the two Nikon lenses we’vealready mentioned, has a
relatively fast and constant
f/2.8 aperture. This makes it
easier to get a shallow depth
RIÀHOG²HVSHFLDOO\XVHIXOIRU
portraiture at the long end of its
zoom range. The other lens is
Sigma’s 17-70mm which, like
the two Nikons, boasts image
stabilisation, and is in the new
C-class (Contemporary) range.
It matches the 17-50mm’s f/2.8
aperture at the short end of the
zoom range, but this shrinks to
f/4 at the long end.For the same UK price as the
Sigma 17-70mm, you could buy
Tamron’s 17-50mm f/2.8
constant-aperture stabilised
lens, although it’s considerably
more expensive than the Sigma
in the States, making it less
good value there.
It’s interesting to note
that Nikon’s 17-55mm f/2.8
constant-aperture lens omits
optical stabilisation, even
though it’s the most expensive
lens in the group. However, it’s
also one of the oldest, and datesback to a time when Nikon’s
pro-grade D-SLRs were DX
rather than FX (full-frame).
As such, it was originally meant
for cameras like the D2X.Aim wider
Two lenses that aim to give you
a wider view are the Nikon
16-80mm f/2.8-4 and the
newer 16-85mm f/3.5-5.6.
Both give an effective shortest
focal length of 24mm rather
t ha n 27m m, so have muc h
better wide-angle potential.
Both are VR lenses, too, and
both are variable-aperture
(whereby the widest aperture
shrinks as you extend through
the zoom range). However, the
newer 16-80mm f/2.8-4 is
about an f-stop faster at any
given zoom setting, and is
considerably more expensive.What to look for
HERE ARE A FEW FEATURES TO PUT ON YOUR WISH LISTULTRASONIC (RING-TYPE) AF
This autofocus system uses two
large rings which are driven by an
ultrasonic frequency to generate
an electromagnetic turning force,
resulting in quick, quiet focusing.ULTRASONIC (MOTOR) AF
This type of autofocus system uses
an ultrasonic motor which requires
drive shafts and gearwheels, which
tends to make it noisier and slower.Jargon buster
A typical 18-55mm DX standard zoom will
give an effective zoom range of 27-82.5mm,
making it capable of adapting to an
enormous range of shooting scenarios and128 March 2016 http://www.digitalcameraworld.com
GEAR ZONE THE BIG TEST