When double diffusing a light with some space between the diffusion materials, what two effects are achieved?

When double diffusing a light with some space between the diffusion materials, what two effects are achieved?

• A. The source becomes softer and exposure decreases
• B. The source becomes harder and exposure decreases
• C. The source becomes softer and exposure remains the same
• D. The source becomes harder and exposure increases

Answer: (A)

The effect being tested is that diffusion makes the light source appear larger and softer, and adding a space between two diffusion layers increases that softness while still reducing the overall light reaching the subject. Each diffusion layer scatters light; when you add a second layer with an air gap, the light spreads more between stages, enlarging the apparent source and wiping out harsher shadows. But diffusion also absorbs and scatters light, so losing some light to the extra diffusion means the exposure drops. So double diffusion with a gap gives you softer light and lower exposure.

The effect being tested is that diffusion makes the light source appear larger and softer, and adding a space between two diffusion layers increases that softness while still reducing the overall light reaching the subject. Each diffusion layer scatters light; when you add a second layer with an air gap, the light spreads more between stages, enlarging the apparent source and wiping out harsher shadows. But diffusion also absorbs and scatters light, so losing some light to the extra diffusion means the exposure drops. So double diffusion with a gap gives you softer light and lower exposure.