Panasonic DFD autofocus on GH5, GH5S, G9: Do you need Panasonic lenses?

Panasonic use contrast detect autofocus in their cameras, which is often described as a poor relative to the Phase detect systems adopted by most of their competition, To improve its performance, Panasonic developed DFD (Depth From Defocus) technology, which is supposed to help. However, it relies on the camera understanding the optical characteristics of the lens, and there's some debate as to how different the autofocus performance is when using 3rd party lenses and Panasonic's own lenses. In this short video, I set out to test this with my Panasonic GH5, GH5S and G9 using both a Sigma lens and a Panasonic lens.