fillflash

Fill flash, or fill-in flash, is a photographic technique in which a flash is used not as the primary light source, but to illuminate shadow areas and reveal detail that would be lost in bright backgrounds. It is commonly used in daylight portraiture and other high-contrast scenes to reduce the contrast between subject and background and create a more natural looking exposure.

How it works: The ambient light provides the scene’s dominant exposure, while the flash adds light to the subject. Photographers can control flash output, distance, and angle. Modern cameras and flashes offer TTL (Through-The-Lens) metering that automatically sets flash power, or shooters can set manual power levels. Bounce lighting or off-camera flash is often used to soften shadows and produce more natural results.

Techniques: For outdoor portraits, the photographer meters for the ambient exposure and then uses a lower-power flash to fill in shadows (often well under the ambient exposure). High-speed sync lets flash be used at shutter speeds above the camera’s default sync speed in bright light. Flash modifiers such as reflectors, umbrellas, or softboxes further soften the look. Off-camera fill can create more directional and dimensional lighting than on-camera flash.

Considerations: Overuse can produce flat images with a lack of texture, so the fill should be balanced with the background lighting. The angle and distance of the flash affect shadow softness and catchlights; color balance should match ambient light to avoid color casts.

Fill flash has been a common technique since early photography and remains widely used in portraits, events, and street photography, aided by modern TTL and portable strobes.