Set one of the human- or animal detect modes. It will work just like the ordinary Auto- or Wide area modes until it detects a face. It will then charge frame colour to yellow as it has changed to face detect. As soon as it detects the eye, the frame will shrink to the size of the eye and follow with this higher precision. It is no longer necessary to play around with the a4 settings unike the single-EXPEED bodies.
Will give that a go and thanks for reply