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Tokina AF 50-135mm f/2.8 AT-X Pro DX - Review / Test Report - Analysis |
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Lens Reviews -
Canon EOS (APS-C)
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Page 2 of 3
Distortion
The level of distortion is reasonably well controlled for a zoom lens.
At 50mm there is relatively pronounced barrel distortion (1.1%) changing to moderate pincushion
distortion (0.9%) at 135mm. At 85mm the two forces even out.
50mm:
85mm:
135mm:
The chart above has a real-world size of about 120x80cm.
Vignetting
The Tokina is a dedicated APS-C lens so vignetting is a little bit more pronounced here
specifically at f/2.8. At 50mm and 85mm the issue is still moderate with a max. vignetting around 0.6EV
whereas the vignetting increases to 0.83EV at 135mm. Nonetheless this is still fairly decent for
such a kind of lens.
MTF (resolution)
The Tokina AF 50-135mm f/2.8 AT-X Pro DX exhibited a very good to exceptional performance
in the MTF lab. At 50mm the resolution is extremely high throughout all tested
aperture settings. At f/4 and f/5.6 the values are even among the highest tested to date on the EOS 350D.
There is a performance penalty at 85mm f/2.8 which affects the image borders (only) but
from f/4 onwards the resolution is superb again. At 135mm there is a slight drop in
performance which also affects the center resolution at f/2.8. The contrast level is also somewhat
affected here. Beyond wide-open aperture the quality is excellent. All-in-all quite impressive.
The lens suffered somewhat from a rather pronounced field curvature which may result in
softer corners when shooting flat objects with a shallow depth-of-field.
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)
The Tokina exhibits relatively pronounced lateral CAs (color shadows at
harsh light transitions) peaking around 0.9px at 50mm and 1.4px at 135mm f/2.8.
Expect that CAs can be easily visible at 135mm especially at the extreme borders
and large aperture settings.
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