When using reflectors, mirrors and bounce cards, you have to treat them just like lighting instruments. This includes the distance they are from the talent. To increase the intensity of the light coming off of a reflector, you need only to move it closer to the talent. To decrease the intensity, move it further away. As in lighting, the way it works is double the distance from the subject and it reduces the intensity of the light four times. Cut the distance in half and the light becomes 4 times more intense.