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Lens review

Tokina AT-X PRO DX 12-28 mm f/4

26 August 2013
Szymon Starczewski

7. Coma, astigmatism and bokeh

The coma decreases with the increase of the focal length. At the widest angle of view you can call it high, at 20 mm it is just medium and at 28 mm it becomes low.

Tokina AT-X PRO DX 12-28 mm f/4 - Coma, astigmatism and bokeh


The astigmatism, understood as the average difference between horizontal and vertical MTF50 function values, amounted to just 5.5%. Taking into account the fact that the chromatic aberration is partially responsible here, because it influences the resolution of the lower border, you can say the tested lens corrects the astigmatism very well.

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The circles created by defocused light points have noticeably lighter edges and a darker centre. It doesn’t influence images outside the depth of field in the good way. As an advantage you can say that the shape of circles in the frame corner isn’t much different from the shape of circles in the centre. What’s important, it is true even at the maximum relative aperture and it indicates that the vignetting is corrected in a proper way.

Tokina AT-X PRO DX 12-28 mm f/4 - Coma, astigmatism and bokeh