Background Light
A light aimed at the backdrop rather than the subject, controlling how bright or dark the background renders.
Measured in
f-stops (EV)
In depth
Because the background is lit independently, its tone becomes a free variable: the same grey paper can be rendered black, mid-grey or pure white simply by changing this light's output. Two stops above the key gives clean white; matching the key gives mid-grey; switching it off gives near black if the backdrop is far enough away.
Examples in practice
Two lights on a grey backdrop metering two stops above the key render it as clean paper white with no retouching.