Exposure

Exposure describes how much light is gathered to form an image: on the sensor of a real camera, or by the virtual camera in a render. In photography, aperture, shutter speed and ISO work together to set it. Physical cameras in render engines either mimic those three values or offer a single exposure value (EV). A good exposure avoids both murky shadows and large areas of blown-out white.

Why exposure matters in rendering

In a physically based scene the sun is enormously brighter than a table lamp. Exposure decides which slice of that wide range ends up as a mid-tone in the picture. For a daytime facade it comes down; for a night scene or an interior it goes up. A common mistake is to crank up the lights instead. Usually the better move is to keep the lights at realistic values and adjust the camera, the way a photographer would.

In practice

When a window is in view, the gap between inside and outside is large: expose for the room and the window turns white. Tone mapping, a little fill light or layered corrections in post-production help balance it. Watching the histogram keeps your eye honest, since screens and tired eyes both mislead. For the wider logic of render settings, see render settings explained.