In difficult situation like this one, the ColorBalanceCoach target played a key role.
I wanted a light rolling on top of my nude model’s stomach. I needed to calculate exactly the light passing horizontal al the model’s point. By putting the ColorBalanceCoach target flat on the floor I was able to preform the necessary readings, and ajust the camera for an exact white balance and exposure setting.
Model: Émilie

Shot at Studio Astre, Paris, France.