I am trying to film the movement of ink droplets in water as well as swirling colors dropped into milk and distored with dish soap. I am using a Nikon D5100. I am new to using my DSLR so i'm not exactly sure how I can get my camera to stay focused on the swirling ink. I had my settings as 'subject tracking AF' for AF-area mode and the focus mode on full-time-servo AF.it had a hard time focusing on the swirling ink as it changed directions.it would keep refocusing but it took a while for it to finally focus (thats if it even could) and i really don't want these blurry transitions in my video.
Can anyone please suggest how I can record this movement with a proper focus?
>>> What video settings should I use to record ink droplets in water?