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ON TRIAL TAMRON
current technologies to deliver a
range of improvements to imaging
performance.
The optical construction
comprises 23 elements in
17 groups with fi ve of these
elements being low dispersion
(LD) types and one being an XLD
type... which signifi es ‘eXtra Low
Dispersion’ characteristics. These
special elements work to minimise
chromatic aberrations – or colour
fringing – by limiting the amount of
dispersion between the different
coloured wavelengths of light
as they are refracted. Chromatic
aberrations can be particularly
problematic with fast telephoto
lenses and Tamron’s design is
intended to be effective across
the lens’s focal range which is
always a challenge.
Tamron’s latest’s ‘eBAND’
anti-refl ection coating is applied
to element surfaces – the name
is short for ‘Extended Bandwidth
And Angular-Dependency’ – and its
special nano-structure layer has an
extremely low refractive index to
further assist with the minimising
of ghosting and fl are. The zoom’s
focusing group is internal – so the
front element doesn’t rotate – and
changes made to the designs of
both the focusing and zooming
cams reduce the minimum
focusing distance by quite a
bit to 95 centimetres which,
at 200mm, gives a maximum
magnifi cation ratio of 1:6.1. For
the record, the previous modelonly focused down to 1.3 metres.
Autofocusing is via Tamron’s latest
version of its ‘Ultrasonic Silent
Drive’ – that’s the USD initials
in the model name – which is
controlled via two processors and
a new algorithm to optimise speed
without compromising accuracy.
It’s a ring-type drive which provides
a full-time manual override for
fi ne-tuning. For even faster AF
operations, there’s a limiter switch
which can be set to lock out the
closest distances from three
metres to the minimum object
distance. Incidentally, this range
can be changed using the optional
‘Tap-In Console’ which is a USB
dock enabling various adjustments
and fi rmware upgrades.STEADY UP
Also new-and-improved is the
optical image stabiliser. Tamron
uses the name ‘Vibration
Compensation’ (VC for short) and
it now delivers up to fi ve stops of
correction for camera shake which
is currently the highest provided
on any pro-level f2.8 speed
70-200mm zoom. There are three
image stabiliser modes for general
shooting, for panning (with the
lens detecting the orientation)
and for engaging only during
an exposure rather than also
when viewfi nding.
The A025’s optical design
has been optimised for use with
Tamron’s new teleconverters – the
1.4x Model TC-X14 and the 2.0x
Model TC-X20 – which increase the
focal range to 100-280mm (with
a maximum aperture of f4.0) and
140-400mm (f5.6) respectively.
Full autofocusing capabilities
are retained.
While primarily designed for
use with full-35mm format sensors
(Tamron uses the designation ‘Di’),
this lens can be used on ‘APS-C’
format D-SLRs where the effective
focal length becomes 105-300mm
(at 1.5x) or 112-320 (at 1.6x).
The G2 70-200mm f2.8 is
currently available in the Canon
EF and Nikon F mounts, the latter
being the G-Type confi guration so
aperture selection is controlled
from the camera body. This is now
standard across Nikon’s D-SLR
line-up, but will preclude the
Tamron’s use on many older digital
bodies from around mid-2007 or
earlier (and all 35mm fi lm bodies).
However, using the G-Type mount
has enabled Tamron to adopt an
electromagnetically-controlleddiaphragm in its Nikon model
and this allows for more accurate
aperture setting – especially frame-
to-frame with continuous shooting.
Incidentally, the aperture range in
both versions is from f2.8 to f22
and the diaphragm itself employs
nine blades to give smoother out-
of-focus effects.IN THE HAND
In terms of its physical
construction the new Tamron
70-200mm f2.8 zoom employs
metal barrel tubes with full sealing
against the intrusion of dust or
moisture. Tamron says it’s using
a new sealant material which is
applied in all the joints to provide
more effective protection against
the elements. A very substantial
gasket protects the lens mount.
Additionally, a fl uorine coating
is used on the exposed surface
of the front element to help repel
both water and grease, and allow
for easier wiping down. Should
you prefer to fi t a protective fi lter,
the screwthread diameter fi tting is
77 millimetres. A bayonet-fi t petal-
type lens hood is supplied.
As is standard in this class, a
rotatable tripod mounting collar
is provided and it’s made from
magnesium alloy to help save
weight. More interesting though,
is that the quick-release plate is an
Arca-Swiss type, thereby providing
compatibility with a wide selection
of pro-grade tripod heads.The new lens’s styling has
been modernised so, for example,
the tripod mount’s collar is fl ush-
fi tting as is the manual focusing
collar and a matte black fi nish give
the whole lens a very clean and
contemporary look. In the hand
it feels very strongly built and all
the barrel-mounted switches (for
the AF limiter, VC on/off, stabiliser
modes and AF/MF) have a crisp,
positive action. The focusing collar
is electromagnetically controlled
(rather than being mechanical) so
it’s smooth in its operation, but
has that slightly disconnected feel
which is a characteristic of these
controls and, of course, there are
no stops. The zooming collar, on
the other hand, feels nicely meaty
and covers the full focal range in
slightly less than 90-degrees twist.PERFORMANCE
Tamron’s claims regarding the
improved imaging performance
of its G2 70-200mm f2.8 are no
idle boast. The centre-to-corner
sharpness is exceptional across
the focal range up to f11 and even
at the widest aperture of f2.8.
Diffraction comes into play at
f16 and f22 so corner sharpness
suffers a little, but it’s still pretty
good and the centre sharpness
remains very good.
In terms of its sharpness, the
new lens is easily superior to the
previous model and on a par with
Nikon’s rather more pricier third-
gen AF-S 70-200mm f2.8 which,
of course, we tested in the March/
April 2017 issue. The Tamron
lens even exhibits Nikon-esque
contrast characteristics which
result in nicely punchy images with
beautifully crisp defi nition.
There’s minimal vignetting
(brightness fall-off) when shooting
wide-open too, and the correction
for lateral chromatic aberrations
is very effective across the focal
range, including when shooting
at the wider apertures. It’s non-
existent in the centre of the frame,
and only occurs near the corners
along very high contrast edges,
but it’s only very minor, suggesting
that all those low-dispersion
elements are doing their job
very well.
Distortion is also well controlled
with slight barrel-type bending
at 70mm which becomes slight
pincushion-type bending at
100mm, but stays absolutely
negligible up to 200mm so it really
isn’t noticeable at all, which isTAMRON SAYS
IT’S USING A NEW
SEALANT MATERIAL
WHICH IS APPLIED
IN ALL THE JOINTS
TO PROVIDE
MORE EFFECTIVE
PROTECTION
AGAINST THE
ELEMENTS.
On-barrel switches select focusing
operations, autofocus range and
image stabiliser modes. Uprated
‘Vibration Compensation’ (VC)
system provides up to five stops of
correction for camera shake.CamMayJune17_054-056 Tamron.indd 55 13/04/2017 8:35 AM