Tokina AF 50-135mm f/2.8 AT-X Pro DX - Review / Test Report - Analysis
Lens Reviews - Canon EOS (APS-C)

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.

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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