After just receiving my new K-5 IIs, I've only had a brief chance to shoot with it in the field. IMO, PF and CA are considerably less with this sensor than with any previous body. I shoot an FA* 300/4.5 + P F 1.7x AFA most often (I'm a birder). The FA* 300/4.5 controls bot PF and DA reasonably well, but the AFA magnifies the color aberrations in high contrast shots.
With the K-5 IIs, my first high contrast shots showed considerably less CA than about 6 years of experience with this lens/TC combo has led me to expect, and little or no PF. Again, this is very preliminary -- less than 200 shots with the new camera so far, and only a few high contrast (birds/branches backilt against a bright sky) Here are a couple of examples -- sharpened a bit to offset downsizing for the web, but no other PP) The CA/PF is wider and a bit more apparent in the full size shots, but not nearly as vibrant or distracting as has been usual. I was experimenting with EV comp to see what the best method of shooting this type of shot might be.
This one I shot at +2 Ev comp and I brought the exposure down in PP. Red/Green CA is evident on the branches, but not to the extent expected -- I expected massive PF on the Nuthatch's head and beak and along the trunk of the tree, but there really is none
This one was shot at 0Ev comp and I brought the exposure up in PP. A little Red CA evident on the tree trunk, but nothing really on the bird. The first shot is more a more accurate reproduction of the frame, but the bird looks a bit better in this one, IMO
This was strictly an ID shot. I didn't bother to get the focus spot on, just wanted to see what the bird was. To the naked eye, the bird was completely silhouetted against the sky. The Sun was setting just out of frame to the left. Shot at +2 Ev comp. This type of shot would usually be a CA/PF mess, but the color aberrations aren't really objectionable at full size, and are hardly noticeable downsized unless you're looking for them.
Certainly not proof by any means, but I think indicative of what I can expect from this camera. It might be the sensor, it might be the processing engine. . . I don't know. . . All I do know is that I expect to be doing a whole lot less correcting for color aberrations in PP with the K-5 IIs. . .
Scott