What proportion is appropriate to adjust the back of the photographic lamp?

Hello, it depends on your needs. If the average portrait requires normal exposure, the stereoscopic impression is not very strong. Adjust the indicator of the lamp to the maximum, and the distance from the drawing is about 1.5 meters. The distance between the figure and the background should be greater than1.5m. If it is too close, the depth of field between the figure and the background is difficult to control. If the character is required to have a three-dimensional tone, that is, the light ratio is stronger, you can dim or pull the light further. While shooting people indoors, you still need outline lights.