Canon 550EX - Manual (Page 25)

Using Flash in Full Auto Mode
After the flash fires, check that the
flash exposure confirmation lamp
lights.
When a correct flash exposure has
been obtained, the flash exposure
confirmation lamp lights for about 3
sec. If the lamp does not light, the
flash may have been insufficient,
resulting in underexposure. In such a
case, check that the pilot lamp is red,
then move closer to the subject and
take the picture again.
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The preflash is fired to obtain an evaluative flash meter reading
The main flash illuminates the subject for the actual picture.
• Fill Flash
Fill flash can be used outdoors in daylight to supplement existing light. It can
soften shadow areas of the subject or illuminate a backlit subject.
With fill flash. Without fill flash.
When fill flash is used, the flash exposure level is reduced automatically so that the
subject's illumination by the flash balances well with the background's ambient light.
Instead of having a properly-exposed subject and an underexposed background, both
the subject and background are exposed correctly for a natural-looking flash picture.
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