Hi, I have got this lens and it is absolutely amazing in regards of image quality. I am only using it with the aperture wide open, mainly for environmental portraits and but I do find that the autofocus is hunting quite a bit sometimes, especially if the subject is further away, maybe full or three/quarter body shots and that there are more images that are not in focus than with lenses that are less wide. I do understand that it is harder for this lens to lock the focus accurately as the subject is obviously much smaller due to the wide angle and that this might be the reason. I have the D810 body set to AF-C S (Matrix metering set to face recognition). Is that the right setting in your view? It works very well with all my other lenses. Any suggestions and advice are very welcome, thanks.