Canon EF-S 17-85 mm f/4-5.6 IS USM
7. Coma and astigmatism
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As we can see in the pictures below and the comparison of the picture resolution in the center and at the edges of the frame, coma is visible (mostly at 17 mm) but at a relatively low level.
We cannot complain about the astigmatism either. The average value is 5.7% with its maximum value in the middle of the focal length range (30-50 mm) and its minimum at the 85 mm focal length. This is probably why the results in that picture resolution category at that particular focal length and maximum aperture were so good.
