Using the advice I got here, I had two set ups. One was my 10-17mm on a 1.4x TC and the other was just my plain old 60mm. No diopters at all. The 10-17mm with 1.4x TC did not work well on tight focus (the combo was too slow) because I found that the best camera set up was my Z240s on full power, ISO 200, 1/200 and f13. If I were using a bigger f-stop the 10-17mm/1.4x TC would have worked well- but I had too much light so bigger f-stops started lighting the water. The sweet spot is governed by making the animals glow without blowing out their internal structures while achieving black water.
Instead, I quickly changed to the 60mm and kept it "pre-focused" for critters about 20cm from my flat port (Wetpixel advice) which was the epicentre of where I had my pilot and focus lights. This was a good trick I picked up from Matt D' Avella of Jack's Diving Locker. Put your hand out and manually focus on your finger when it is brightest (when it is at the epicentre). When the critters come by, you steer the epicentre to them and then when they glow, depress the shutter halfway and let the 60mm/camera fine tune the focus. By pre-focussing, you prevent hunting (especially when the Copepods start to swarm). Only subtle adjustments to f-stop needed. Leave the speed alone.
Matt told me during the dive briefing to start at 1/160 and f15 or so with the maximum strobe and focus light output possible. The critters are not that swift so he said ISO 200 is good. He recommended adjusting from there, but not adjusting speed unless you run out of f-stop. He said to prefer f stop so that you don't start chasing your tail. He does this with his video- he just winds iris around using the maximum light he can take down with him.
We will definitely do this dive again on our next trip back from the east. It is too easy to duck into Kona and chill out for a few days on the tail end of a big dive trip. The dive is very easy and comfortable. Just a quick stroll from the hotel and a short van ride to the boat. The deep water is 4-5 miles off the coast, so you are there and back in a few minutes. We ended up chartering the whole boat (paid for four spots rather than just two) to make sure it went out both nights. This meant we had a relaxed time with Matt and the crew who are all experienced photographers/videographers. Plenty of great advice on how to have a great dive and take good shots.