I did my focus points manually actually ....
It can be very hard to be sure that one has accurately overlapped acceptable focus in all areas.
Helicon sells a utility called Helicon Remote that is very useful in this regard.
It does require tethering to a computer though.
What one does is show the software the near and far limits of required focus.
The software detects the lens focal length, f stop etc and can then precisely calculate the focusing intervals required (these are not like regular fence posts but closer together the closer one is to the camera and further apart as one moves away from the camera).
The software will also control the camera and execute the series of shots appropriately.
Helicon Remote will also do HDR sequences, either in isolation or in combination with the focus stacking.
Another possible solution is the Promote Control programmable remote (useful where tethering to a computer is impractical).
Although accurate shooting may not completely eliminate the possibility of artifacts it does give the software the best possible starting point.
Regards
Tony Jay