This is a really simple technique but incredibly effective. All you do is put a reflector or a piece of polyboard under the talent’s face. Here’s an example frame from Ren starring Sophie Skelton. This was shot on an overcast day using a 2.5K HMI as backlight.

Sophie is very beautiful and the make-up (by Becca Youngs) is great, but the icing on the cake is a simple piece of polyboard out of the bottom of frame. It subtly lifts the shadows on her face and puts a ‘sparkle’ in her eye. That sparkle is actually the poly’s reflection, but it’s amazing how much life and energy that gives. I’m calling this technique the Health Bounce because it’s used a lot in ads for health and beauty products.

Here’s a side-by-side comparison without (left) and with (right) the poly.

The human brow has evolved to protect our eyes from sunlight, amongst other things. In an exterior scene, particularly on an overcast day, the light comes predominantly from above, rendering the forehead and the nose the brightest areas, and throwing the eye sockets into shadow. This is a challenge for cinematographers. So much of an actor’s performance is in the eyes – it’s essential to get light into the eye sockets to capture every nuance of that performance. A bounce board underneath the face helps do that.