I’ve been experimenting a bit trying to reducing the effect of Green/Cyan CA with the FX9. I have discovered a couple of things that can help reduce interactions between the cameras processing and areas of high contrast that may be exhibiting bright green/cyan fringes.

First thing to note is that a lens with less or no CA will not have the same issue. But as no lens is totally CA free the below settings can help.

These changes are for Custom Mode Only.

1: Turn OFF the aperture correction in the paint menu. Turning off the aperture correction noticeably reduces the cameras tendency to create black halos in areas of extreme contrast and it also reduces the enhancement of areas of strong CA. This has a softening/smoothing effect on bright CA making it much less noticeable. There is very, very little loss of sharpness in the rest of the image and I actually prefer the way the camera looks with this turned off.

2: Use the Multi-Matrix to reduce the brightness of Green/Cyan CA. The most common examples of CA causing an issue are with background out of focus high contrast areas. In this case the CA is normally Green/Cyan. It’s possible to tune the cameras multimatrix to reduce the brightness of these green/cyan edges. If you turn ON the mutli-matrix and then select CY+ and set this to -30 you will see a very useful reduction in the intensity of the CA. For a stronger reduction in addition select CY and set this to -15. 
Changing these setting will have an impact on the reproduction of other cyan objects in your shots, but you should see this in the VF and testing various scenes these changes are typically not noticable. In some cases I am finding I actually like this slightly modified look!

Use both of the above together for the strongest impact. But if you are only going to use one, turn off the aperture correction.