Slow-motion camera slows kitties WAY down
That is a hard question in itself. Slow motion is widely understood to be a game of chance because the most interesting stuff in slow motion is often the least controllable. I suppose getting particle materials like water, dust, sand, et cetera, to react in specific manners can be pretty challenging. Also, filming small fast moving objects with precision can me tough. Bugs, for instance, can be really challenging to catch mid-flight . Ha ha. I once had a fly buzz into a macro field of focus only barely wider than the fly itself, then it proceeded to fly from one side of the screen to the other completely in focus. To this day I consider that my luckiest shot.