Fill Flash

A fill flash is usually used lightly as the available light should still be image effective. Often an untrained eye cannot see that a flash was used. The natural lighting mood should be captured whenever possible. The fill flash is often used depict a great subject contrast by brightening deep shadow areas (e.g. sunlight, to brighten under eye shadows).

In order not to let the light from the flash be too dominant, careful use of the flash compensation is required.

Areas of use for fill flash

  • To reduce subject contrast
  • Accentuate image areas in the foreground through additional light
  • Reduction of unwanted shadows (e.g. under eye shadows when the sun is high)

The camera’s flash sync speed can restrict the choice of diaphragm if the surrounding lighting is very bright. The flash synchronisation speed is the shortest amount of time the camera can fully open the shutter. Faster shutter speeds do not cause the shutter to work faster, the cameras uses a trick and only open the shutter curtains a crack (focal plane / focal plane shutters) and transmit the image via image sensor or film. For the exposure, this usually results in the same effect a faster shutter would deliver. If there are fast moving objects in the image, this can result in motion blurring.  For flash photography as well, this technical background information is relevant. As a flash only emits light for a very short amount of time (a fraction of the fastest shutter speed on cameras), only the area of image that is hit by the light of the flash is illuminated with an exposure time that is faster than the flash sync speed.

Note: For the leaf shutter the same problems with the flash synchronisation speed do not apply.


Geese at the beach – Crete – Greece 2003

This photo was taken in Crete.  Due to the backlighting, there was a high subject contrast.  If a fill flash or a different brightening technique (optical brighteners, reflectors…) hadn’t been used, it would have resulted in an overexposure of the horizon or an underexposure of the geese. Additionally, only the geese’s silhouettes would have remained visible. The cast shadow on the white goose indicates that a flash was used.