This page emphasizes performance at f/1.8, but also offers some stopped-down comparisons.
Stunted tree by vernal pond
Sharpness is adequate to show a small group of tiny insects flying in the air near this small tree. The sharpness extends impressively well to the edges of the frame.
Control of secondary longitudinal chromatic aberration (magenta/green blur on out of focus areas) seems quite well controlled. See Making Sharp Images.
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