To make subjects ‘pop out’ while muck diving, we often have to separate the subjects from the distracting background (often sand), and sometimes this can be done with using only one strobe (or video light) instead of using two. When using two strobes, we light up the whole area (unless we use advanced techniques) whereas when using one strobe only, the subject can produce a black background by creating a shadow.
Painted frogfish (Antennarius pictus) lit up with two lights, one from the left and one from the right side. The light on the right side illuminates the frogfish’s chin and left eye, as well as the sand and surroundings.
Painted frogfish (Antennarius pictus) lit up with one light from the left only. The frogfish creates a shadow and we separate the subject with a black background from its surroundings.
It is also easier to play around with strobe positions when there is only one. I’m not saying that you shouldn’t use two strobes at all, but sometimes it is nice to try something different. Even if you have two strobes connected to your rig, you can always switch one off and give it a try.
Here’s a short video to show the difference between using one light vs. using two.