It seems to be conventional wisdom (or as close as we can come to conventional wisdom about a relatively new phenomenon) that the PDAF striping in the Sony a7III only occurs at wide apertures and with fast lenses. Rishi Sanyal was kind enough to run a series of images of an overexposed circular light source with the a7III and the Sony 85mm f/1.8 lens.
Here are the results of my PDAF striping analyzer, with the raw G plane mapped to the sRGB blue plane, and the raw G2 plane mapped to the sRGB red plane:
The conventional wisdom is not always correct. I have 3D plots if anyone is interested, but the above tells the story pretty well.
So, Jim, what would conclude the impact of this will be on image quality?
For normal photographers, 99.99% of the time, none at all. For people routinely shooting into bright lights, sometimes but infrequently. I’ve never seen any problems in real world situations. There are fixes if it happens, like the one recently added to raw Therapee. Rishi’s a7III image showed the issue far more than I’ve seen it in the a7RIII, even in the lab. Could be a freak situation. Could be something different about the a7III.