When you have strong light from one side, adding a reflector of some sort on the other side can bring back detail on the dark side. Often you have to get that reflector as close as you can.
You can use almost anything white or near white as reflector, including cardboard, foil, mirrors, even a building or a truck.
Bottom Line: Look for reflectors to add light back in on the side away from the light source.
100mm, f11
Left
Right
Direct flash with no reflector on the dark side of the face — pretty harsh light.
Direct flash with reflector on the dark side of the face — shows more detail on the dark side, but leaves large dark areas.
Large umbrella on left, no reflector
Umbrella with no reflector on right.
Large umbrella on left, with reflector.
Softbox on left, no reflector on right.
Softbox on left, with reflector.
Softbox on left, with reflector.
Bounce light with reflector.
Direct flash with no reflector on the dark side of the face — pretty harsh light.
Direct flash with reflector on the dark side of the face — shows more detail on the dark side, but leaves large dark areas.