N-Photo - The Nikon Magazine - USA (2019-07)

(Antfer) #1

What to look for...


Keep these on your superzoom wish list


LONG REACH
The DX format lenses on
test stretch to 200mm,
300mm or 400mm. After
applying the 1.5x crop
factor, the ‘effective’
focal length becomes
300mm, 450mm or
600mm respectively.


OPTICAL
STABILIZATION
All but essential in
superzoom lenses,
competing stabilization
systems include Nikon
VR (Vibration Reduction),
Sigma OS (Optical
Stabilizer) and
Tamron VC (Vibration
Compensation). A lens
with a built-in optical
stabilizer has a dedicated
group of elements with
computer-controlled
movement to counteract
physical vibrations.

FOCUS DISTANCE
SCALE
M o s t l e n s e s i n th i s g ro u p
have a focus distance
scale, either mounted
under a viewing window
or printed on the focus
ring. However, they are
lacking in the Nikon
18-300mm and Tamron
18-200mm lenses.

ULTRASONIC MOTOR
U n li ke i n r i n g-t yp e s ys te ms , a n u l tr a s o n i c
motor assembly uses drive shafts and
gearwheels to drive autofocus. They’re
generally slower and louder in operation.

AUTOFOCUS
SYSTEM
T h e l e n s e s o n te s t w i th
ring-type ultrasonic
systems have the fastest
and quietest autofocus,
whereas motor-based
systems enable a smaller
more lightweight lens
construction.


SEALED MOUNTING PLATE
All of the Nikon and Tamron lenses on
te s t h ave a we a th e r-s e a l r i n g o n th e i r
mounting plates, to avoid the ingress of
dust and moisture. It’s lacking in both
of the Sigma superzooms.

SHORT STUFF
Most superzoom lenses
for DX format cameras
have a shortest focal
length of 18mm,
equivalent to a 27mm on
a full-frame camera.
The Tamron 16-300mm
shrinks to an effective
24mm focal length.


ny zoom lens represents a bit of
a compromise in image quality,
compared with a fixed focal
length prime. It’s only natural
that the bigger zoom range of a superzoom
lens tends to result in a greater
compromise, especially in terms of
sharpness and distortions. But, recent
designs aim to capitalize on advances
in tech, maximizing performance.
A key element in the design of
superzoom lenses is the use of ‘aspherical’
elements. Instead of having the natural
curve of a section of a sphere, these
specially moulded, or ground elements,
have irregular shapes. A single aspherical
element can replace multiple spherical
elements, greatly reducing the size and

weight of a camera lens, while also
potentially increasing quality.
Given that Nikon DSLR cameras don’t
feature sensor-shift stabilization, another
key ingredient in superzoom lenses is
optical stabilization. If you want a lens that
you can use for shooting on holiday or while
travelling, you don’t want to be lugging a
clunky tripod around with you everywhere.
Effective optical stabilization can be a major
asset in getting consistently sharp handheld
shots, especially at long telephoto focal
lengths. All of the lenses in this Big Test
feature stabilization.
We’ve come to accept autofocus as a way
of life in digital photography. However, there
are various competing systems on offer. All
of the Nikon lenses on test use ring-type

ultrasonic AF systems. They’re based on a
pair of large rings within the lens that are
driven electromagnetically at ultrasonic
frequencies. Performance tends to be quick
and whisper-quiet and there’s a handling
benefit too. The focus ring doesn’t rotate
during AF, so you don’t need to keep your
fingers clear while handholding the camera
and lens. Full-time manual override of AF is
also available, without the need to switch
from AF to MF.
The Sigma lenses on test use ultrasonic
motor-based AF systems. These enable a
smaller, more compact physical
construction but the focus ring rotates
during AF and doesn’t allow full-time
manual override. AF tends to be slower
and more audible as well.

Superzoom design


Superzooms use a lot of tech to ensure image quality remains stellar


A


Zoom extremes
Here’s how the major focal length
differences look in practice

The above series of photographs shows the approximate
difference in wide-angle potential between the varying focal
lengths of 16mm and 18mm on an APS-C format body, as
well as the longest competing zoom settings of 200mm,
300mm and 400mm. On a full-frame body, the Nikon AF-S
28-300mm f/3.5-5.6G ED VR lens gives just roughly the
same zoom range an 18-200mm lens allows for APS-C
format cameras.

28mm

18mm

200mm

300mm 400mm

16mm

BIG TEST

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