Canon 550EX - Manual (Page 26)

2. Using Flash in Other Camera Modes
Flash photography is also automatic in the other picture-taking modes. In the
Av (aperture-priority AE), Tv (shutter speed-priority AE), and M modes, the
E-TTL autoflash system sets the flash exposure automatically. The camera
sets the necessary shutter speed (in the Av mode), aperture (in the Tv mode),
or flash output (in the M mode). Flash photography is as easy as normal AE
picture-taking.
Shutter Speed and Aperture Settings for Picture-Taking Modes
Camera Mode Shutter Speed Flash Aperture
Av Automatically set (30 sec - 1/X sec.) Manually set
Tv Manually set (30 sec. - 1/X sec.) Automatically set
M Manually set (bulb, 30 sec. - 1/X sec.) Manually set
Manually set: You set it yourself
Automatically set: Set automatically by the camera.
1/X sec.: Maximum sync speed, (see page 124)
When the shutter button is pressed completely, a preflash fires to obtain an evaluative flash
meter reading for setting the optimum output of the main flash.
The background’s exposure is set with the shutter speed and aperture combination
0 - If the camera is set to the □ mode (Full Auto), the shutter speed and aperture will be
set in the same way as in the P mode (Program AE).
• If the DEP mode (depth-of-field AE) is used with the 550EX, it will be the same as
using the P mode (Program AE).
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