>>4248374both of these lenses exhibit field curvature towards the camera the the edges, you can see it in the undergrowth in the nikkor shot, and really plainly in the woodchips on the canon shot.
>bit swirlythat's called coma, and is the result of the deviation between the sagittal and tangential mtf curves increasing as you move away from the centre of the frame (the blue and black lines)