I have no direct experience in filming this subject but, if it were me, I would try the following :-
Multiple exposure: Film the subject a few times with different exposure (brightness) and overlay the clips in your editing programme. You’ll need a rock solid tripod and/or something to line up the edge of your frame. Try gaffer tape on the workbench at 2 opposite corners of the frame.
Manually focus the camera before shutting down the exposure or applying the ND filter(s). The focus shouldn’t change. If you can’t focus with the iris wide open and the lens on extreme wide angle then maybe you are just too close to your subject.
Experiment with manual focus and how it’s affected by the zoom control and exposure/iris/f-stop in a more friendly environment like a flower vase in the middle of the dining room table.
Please excuse my poor English. I’m ………er English 😉
