Electronic exposure boost when backlight dominates the scene — sensor exposes foreground correctly instead of fighting overexposure. Quick field solution when adding light isn't an option.
Backlight compensation intervenes when the sun or a strong light source is directly behind your subject and the camera sensor gets trapped: it measures the brightness of the background, dims the exposure — and your face in the foreground becomes a dark silhouette. The camera's electronics compensate for this by specifically brightening the front area of the image, while consciously accepting the overexposed background.
This works on a simple principle: the sensor doesn't work with all-over metering, but rather weights the central or lower image areas more heavily — that's usually where your interview subject or the important action is. Modern cameras have this function as a menu option (often labeled BLC or Backlight Mode), and on some models, it's also quickly accessible via a button on the body. You press it, and the exposure immediately kicks in — useful for quick shifts between indoors and outdoors when there's no time for neutral density filters.
On set, this has its limits: backlight compensation is an electronic workaround, not a substitute for proper lighting management. If you use it, you risk the background completely blowing out — especially with bright sky areas. The camera's dynamic range doesn't increase; you're just shifting where the clipping occurs. For documentaries or live situations (press conferences, sports broadcasts), this is often acceptable because you can't position a gaffer with reflectors. In controlled productions, I would instead place a fill light (reflector or LED panel) in the foreground — this gives you more control and better image quality.
Practical tip: test the compensation beforehand with test shots. Some cameras overdo it, others are too conservative. When backlight compensation is active, check the histogram to see where the highlights are landing — you'll see the right side of the graph becoming denser. For critical scenes, I would also turn on the zebra display (flickering overexposure warning) to see exactly where it's clipping. Backlight compensation is fast, but not subtle — use it consciously, not reflexively.