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Tokina AF 16-50mm f/2.8 AT-X Pro DX (Nikon) - Review / Test Report - Analysis |
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Lens Reviews -
Nikon / Nikkor (APS-C)
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Page 2 of 3
Distortion
At 16mm the lens shows fairly heavy barrel distortion (~3.55%) - this is slightly
higher than average but then we're also talking about 16mm here rather than 17mm or
18mm. Beyond the extreme wide-end the distortion is actually very well controlled
with slight barrel distortion at 24mm and slight pincushion distortion at 35mm
and 50mm.
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Move the mouse cursor over the focal length text marks below to observe the respective distortion
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| 16mm |
24mm |
35mm |
50mm |
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The chart above has a real-world size of about 120x80cm.
Vignetting
The Tokina is a dedicated APS-C lens but thanks to its rather large front element
vignetting is generally pretty well controlled. The weak spots are at 16mm @ f/2.8 (1.1EV)
and less so at 50mm @ f/2.8 (0.74EV). At all other tested settings vignetting is not
field relevant.
MTF (resolution)
The Tokina produced very high but also quite mixed resolution figures in the lab.
At 16mm the center performance is excellent to absolutely superb whereas the border
and corner performance is only good at f/2.8 and very good from f/4 onwards.
The borders improve at 24mm and more so at 35mm and the center performance remains
very high. At 50mm @ f/2.8 the border quality drops again although the center
resolution stays on a very good level. Stopping down helps to recover the borders
to very good figures at f/4 and excellent quality at f/5.6 and f/8. The general
sweet spot of the lens is reached around f/5.6.
It is worth to mention that the lens suffered from a slight centering defect towards
the long end of the zoom range. A fully valid sample may have a slightly better border
performance at large apertures.
Please note that the MTF results are not directly comparable across the different systems!
Below is a simplified summary of the formal findings. The chart shows line widths per picture height (LW/PH) which can be taken as a measure for sharpness.
If you want to know more about the MTF50 figures you may check out the corresponding Imatest Explanations
Chromatic Aberrations (CAs)
CAs (color shadows at harsh contrast transitions) are the primary weakness of the Tokina.
At 16mm @ f/2.8 the CAs peak way beyond 2.5px on the average at the image borders. Stopping
down improves the problem quite a bit without resolving it. At longer focal lengths
the CAs could still be better at f/2.8 but beyond from f/4 onwards it is generally well
controlled. Due to the mentioned centering defect the CAs are quite uneven at 50mm.
Here's a 100% sample portion of a shot taken at 16mm @ f/8:
Flare
So far Tokina lenses had a rather bad reputation when it comes to strong contra light.
However, the AF 16-50mm f/2.8 AT-X Pro DX seems to be reasonably resistant against
flare. Here's a 100% sample portion of a shot taken at 38mm @ f/8:
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