Two ways to do the same thing.

[Ashwin]

Cheers Ashwin, I think I deliberately put it in to make the grass look nicer but I can put it back again.

This you can achieve selectively

[arith]

That is very good Ashwin; I've been looking at the difference between blending with screen and not raising fill light or raising with fill light and blending normally. I think screen wins but this leaves a lot of noise behind or that could be my imagination. Essentially if I manage to reduce CA so that it is unnoticeable at 100% I think I will have done very well considering the high contrast. Much harder to get it to look like it did when shot since really the bird is a silhouette.
However, it gives me something to do

[arith]

Sorry, no, I don't know as I wasn't using it for this technique last time.

If you use free transform after selecting scale the edges snap to the sides. cheers