GFA Lighting and Electric Practice Test

Soft light comes from diffusion by scattering photons across a larger area, which smooths and broadens the shadows. When you add a second diffusion layer, you’re putting another barrier in front of the light, so even more photons are scattered or absorbed before they reach the subject. That extra layer reduces the total light that makes it through, so the brightness drops while the light remains soft. The main trade-off with double diffusion is softer illumination at the cost of lower overall light output.

Diffusion isn’t known for increasing color saturation, narrowing the beam, or raising color temperature. Those effects aren’t the typical or intended outcomes of using double diffusion.