Publicidad
Correzione dell'esposizione flash
80
Flash exposure correction
Corrección de exposición
Automatic exposure systems are based on a reflection fac-
tor of 25%, this being the average degree of reflection for
subjects shot with flash. A dark background that absorbs a
lot of light, or a bright background that bounces off a great
deal of light (e.g. backlit scenes), can result in overexposure
or underexposure of the subject, as the case may be.
Exposure corrections in auto mode
To compensate the above described effect, exposure can
be corrected by opening or stopping down the camera's
aperture. If the background is mainly bright, the flashgun's
sensor
will cut off the flash too soon with the result that
the subject will be underexposed. With a dark background
the flash is cut off too late so that the subject looks too
light.
Bright background:
open the camera's aperture 2 to 1 f-stop
(e.g. from f/5.6 to f/4)
Dark background:
Close the camera's aperture 2 to 1 f-stop
(e.g. from f/8 to f/11)
Publicidad
Capítulos
