The lens correction setting for CA in ACR 6.2 does nothing to correct for the CA, shown inside the red circle on the image. (What kind of CA is this?)
Hi Rajan,
It's longitudinal CA. You can see not only magenta 'fringes' in front of the plane of focus, but also green behind that plane (look at the top left). It shows most when (high)light areas are surrounded by dark areas. Overexposure makes it seem worse.
Longitudinal CA is the more difficult to correct than lateral CA, because it's size varies with distance from the focal plane instead of with radius from center, and it is not simple (although it can be done to some degree) to extract depth info from a 2 dimensional image. The simple approach is to watch out for overexposure, use a defringing type of correction, and selectively adjust saturation and/or color where it's most distracting.
The only way to really suppress it is by using a narrower aperture, on the 85mm f/1.2 it's almost gone at f/2-f2.8, but of course that will defeat the purpose of shallow DOF a bit (although at f/2.8 there is still little DOF when shooting close up). Here a full frame 24x36mm sensor also has a benefit because one can shoot from a shorter distance to fill the frame with the same crop as with a cropped sensor, which produces shallower DOF.
Cheers,
Bart
