Light also has its dark sides
Nothing can compete with the sun as the brightest source of light. But problems can arise when the sun is “incorrectly positioned” in the sky – at least from the photographer’s standpoint. The subject can be located in a shadow area or it may be necessary to shoot against the light. To obtain a balanced exposure in such situations it is necessary to brighten up the foreground with flash – a technique that is known as fill-in flash.
When the sun is quot; incorrectly positioned in the skyne the subject can be located in a shadow area.
Use of flash in broad daylight: the flash unit helps to lighten those areas where the sun had just thrown shadows
Fill-in flash in automatic mode
Use the camera or an exposure meter to establish the necessary aperture and shutter speed for a normal exposure with the existing ambient light. The shutter speed must equal or be slower than the fastest flash sync speed. This can vary with each camera model.
Let us assume the following settings: An established aperture of f/8 at a shutter speed of 1/60 s. These two values can be set without any problems if the camera’s flash sync speed is 1/90 s because the shutter speed is then slower than the flash synchronization speed.
The intensity of fill-in flash can be varied in increments so that the character of the shadows can be retained in the exposure. For this purpose simply select an automatic aperture on the flash unit that is one f-stop smaller than the aperture set on the camera. If a camera aperture of f/8 was established, then the correct aperture for the flash unit would be 5.6.
Fill-in flash in TTL mode
Fill-in flash is also possible in the TTL mode. However, the effect of the fill-in light depends upon the characteristics of the given TTL system. The great diversity of the TTL flash controls integrated in modern cameras makes it virtually impossible to give application examples for this purpose.
Fill-in flash in manual mode
For frontal fill-in flash use the camera or exposure meter to detect the aperture that is necessary for the camera’s flash sync speed. Set this aperture on both the camera and the flash unit. Establish the flash-to-subject distance with the aperture calculator of your flashgun or calculate it with the guide number formula.
Close down the camera’s aperture by 1/2 to 1 f-stop if important parts of the picture will be exposed by both the flash and the ambient light.
To vary the intensity of fill-in flash establish the aperture and shutter speed necessary for flash synchronization and adjust these values on the camera and flash unit. The illumination distance is found out with the help of the aperture calculator on the flash unit or it is calculated with the guide number formula. However, in this case the ISO number on the flash unit must be doubled (e.g. ISO 100 to ISO 200).
If you use a flash unit like the Metz mecablitz 58 AF-2 digital that can emit flashes in small partial light output increments the required fill-in effect can be controlled within much finer limits.