20mm on OMD concerns

Here's a couple of pics I took with the 20mm. It's sharp, but the slow focus, the purple fringing and the banding really hurt it when you want to use it most. It's sort of OK if you post process carefully, but it's annoying.

You can see the purple all over this image, even though this is not a worse case scenario with something like wire mesh set in front of the sun.

Purple fringing, tree trunk on top right.

is one of the worst pictures I've taken of it.  It's bad when you try to go for a dramatic shot of something bright against dark shadows.

Banding at ISO2500, also purple fringing on all the lights.