The camera is pointed at the person and the flash is fired. Full frontal flash shots are usually characterized by harsh, sharp-edged shadows. Such "shadowy figures" can be kept out of the picture by indirect flash which is aimed away from the person at a wall or the ceiling so that it is bounced back to the subject - hence the term bounce flash. Direct the flash from the shooting position at a point that is approximately one quarter of the flash-to-person distance. The light reflected in this manner produces an agreeably diffused effect for soft, uniform illumination of both the subject and the background. Obviously, the reflection surface selected must be white or color neutral, otherwise there will be the danger of color casts. For instance, flash bounced off a mat pale green ceiling will give people a "sea-sick" appearance.
If the selected reflection surface is textured, then it would be advisable to use a Metz bounce diffuser instead. This is because a textured surface can produce fine shadows on the exposure. The light intensity of bounce flash is reduced as a result of light reflection and the extended distance the light has to travel before it reaches the subject. The most favourable aperture in the automatic flash mode can be easily established by manually firing a test flash while simultaneously observing the correct exposure display. In manual mode it will be necessary to either read the f-stop on the camera's aperture calculator or to calculate the aperture with the guide number formula.
Bounce flash can also result in undesirable and unsightly effects, for instance in portraits shadows can be formed under the nose and inside the eye sockets. This problem can be overcome by the secondary reflector which directs extra light at the subject in addition to the light from the main reflector. Use of the secondary reflector is only worthwhile if the main reflector is directed away from the subject!