Same situation here! (Optex + 12-35 + Gh4) I've tested on this lenses: 14-42 kit, 12-35, FD 50 1.4 , FD 24 2.8, oly. 45 1.8 I think that modern lenses work best with this kind of anamorphic adaptor. For me 12-35 as wide as possible (around 20mm for no vignette) and f8 or similar get good image. (best of all of my lenses by far) My optex unit came with rear element fliped (reverse hack for close focusing) and terrible image quality. After fitting and aligned correctly the image get very decent. My advice is to put optex on the taking lens as close as possible , and with de 58mm threat direct to the 12-35 seems to hit the rear element of the optex again the front of the 12-35, so i'm using a 58-58 step ring (cheap UV filter without glass ?). Need time for more test, but would be great if we could share our results @ROMSPROD sorry for my english, i'm from Spain.
