Tokina AT-X PRO FX SD 70-200 f/4 VCM-S
3. Build quality and image stabilization
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The Tokina AT-X PRO FX SD 70–200 f/4 VCM-S starts with a metal mount which surrounds an immobile rear element, about 30 mm in diameter. That element is hidden about 1.5 centimeters deep and you can see a black, well-matted, ribbed tube around it. The interior of that construction is fully sealed so there shouldn’t be any problem with dirt getting inside.
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The proper tube is also made of metal; it begins with a smooth ring featuring a white dot to make the alignment with a camera body easier. The next ring, also immobile, has rubber ribbing for a secure and comfortable grip. Behind it there is a smooth casing part which, at first glance, seems to be just a place to fix a tripod; in fact it features a focusing mechanism switch (AF/MF) and a stabilization switch (VCM ON/OFF).
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Further on you see a zoom ring which is 35 mm wide. Most of it is occupied by rubber ribs and below you can find focal length markers at 70, 85, 105, 135 and 200 mm. The ring works smoothly and is well-damped in the whole range.
The next part is a plaque with the name, parameters of the lens and a distance scale behind a window expressed in meters and feet. On the opposite side you see the serial number of the instrument and info that it was produced in Japan and its filter diameter amounts to 67 mm.
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Then you see a manual focus ring, as wide as 47 mm and covered by rubber ribbing. Fortunately the lens doesn’t feature any One-touch Focus Clutch Mechanism so the ring has to be moved upwards and downwards, like in many other Tokina lenses. It works in both AF and MF modes and its performance remains beyond reproach: every move is smooth and well-damped. Running through the whole distance scale takes a turn through 180 degrees – for a lens with an autofocus it is a good result.
Behind the manual focus ring there is only a golden strip and a hood mount. The front element of the lens is 58 mm in diameter; it doesn’t move and is surrounded by a non-rotating filter thread, 67 mm in diameter.
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When it comes to the optical construction you deal here with 19 elements positioned in 14 groups. Three of them are made of low-dispersion SD glass. Inside there is also a round aperture with nine diaphragm blades which can be closed down to f/32.
Buyers get both caps and a hood in the box; it is a more modest kit than that of the rival Nikkor, which has also a case. If you are interested you can additionally purchase a special tripod adapter (TM-705).
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Opitcal stabilization
The Tokina AT-X PRO FX SD 70–200 f/4 VCM-S is the first lens of this producer with an optical image stabilization system. Although other companies have started their adventure with stabilization earlier, usually their declared efficiency at first hovered around 2-3 EV. Tokina started late but they ambitiously claimed 4 EV efficiency – a high standard indeed.
Of course we decided to check that claim. In order to do it we took several dozen photos at 200 mm focal length in the range from 1/200 to 1/5 of a second with the stabilization switched on and off. Then we determined a percentage of blurred photos for every group and presented it as an time exposure function graph, expressed in EV (with 0 EV being the equivalent of 1/160 of a second).
The graph above shows clearly that a value of 4 EV remains just a dream. The real stabilization efficiencyof the Tokina amounts to about 2.5-2.7 EV –by today’s standards a medium result, noticeably worse that the results of the direct rivals.
