My advice: just don't use autofocus when shooting with a DSLR (yes, I realize it's technically a mirrorless camera--the principle is the same). Autofocus on stills lenses relies on contrast detection, and is inaccurate, slow, and half the time will not focus on what you need it to. Learn to focus manually, and/or get a small follow focus rig, and you will be INFINITELY happier with the results.
This may not be the answer you're looking for, but it's the only good solution. There is no camera setting that will improve the AF performance of a stills camera enough to make it practical to use with good results.