When set to perform Post Focus, the GX8 (and some other upcoming models and firmware updates) shoots 50 images at 30 fps with the focus point changed in each one. This function requires a DFD capable lens (Depth from Defocus). When a Post Focus image is reviewed, you tap on the point you want in focus, and the camera creates a new image with that point in focus. In essence, the camera is doing a focus rack during the 50 shot sequence, then letting you pick the appropriate image from any of the images shot.
It strikes me that this is the least useful of the possible uses of this function. A more useful option would be focus stacking, or using the individual shots to create a deeper of very specific depth of field, as we often do with series of shots in macro.
While Panasonic’s firmware is not yet complete, it appears that the 50 images do stay on the camera, so we can probably use them to focus stack after the fact. However, Panasonic really doesn’t have anything useful in the way of a macro lens that understands DFD, which apparently is necessary for this feature to work. It would have been more interesting to see a new longer focal length macro lens (say 60-80mm) being developed than yet another “normal” focal length lens (e.g. 25mm f/1.7).
It really feels to me that camera designers are tracking each other’s features rather than developing true photographic improvements. It’s the old Marketing Check Box game in action. The “touch to refocus” aspect of Post Focus appears to be a response to Lytro. Why? I don’t know. Lytro isn’t exactly setting the world on fire. Indeed, if Lytro is a match, someone dampened its head and then put it in the freezer. So why imitate that? Why not target a thing that photographers are actually doing (focus stacking) and more would like to do?