[Brightcolours]

I very much doubt that RSA will be the issue causing missed focus images with mirrorless cameras.

 

Anyway, some mirrorless cameras miss focus consistently when the lens focusses coming from one end, not the other end of the focus range. This points to inaccurate back steps after the contrast AF saw that best contrast has been passed.

 

Other cameras (like Sony MILCs) seem to totally miss focus without a real clue as to why sometimes.

 

And some focus just fine.