E-TTL II / E-TTL Autoflash, by Shooting Mode
E-TTL II or E-TTL autoflash suitable for the current shooting mode is used automatically – simply set the camera shooting mode to 
(shutter-priority AE), 
(aperture-priority AE), 
(flexible-priority AE), or 
(manual exposure).
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Select this mode when you want to set the shutter speed manually. The camera sets a suitable aperture value for the shutter speed to obtain standard exposure based on metering by the camera.
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Select this mode when you want to set the aperture value manually. The camera sets a suitable shutter speed for the aperture value to obtain standard exposure based on metering by the camera.
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Any shutter speed or aperture value can be set.
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Select this mode if you want to set both the shutter speed and aperture value manually. Light from the flash provides standard exposure for subjects. Background exposure varies depending on your specified shutter speed and aperture value. |
When shooting with 
or 
, the result is the same as flash shooting using 
(Program AE).
Flash sync speed and aperture value, by shooting mode
| Shutter Speed | Aperture Value | |
|---|---|---|
|
Set automatically (1/X sec. to 1/60 sec.)*1 | Set automatically |
|
Manually set (1/X sec. to 30 sec.) | Set automatically |
|
Set automatically (1/X sec. to 1/60 sec.)*1 | Set manually |
|
Set manually / automatically (at least 1/X sec.) | Set manually / automatically |
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Set manually (1/X sec. to 30 sec., Bulb) | Set manually |
1/X sec. represents the camera's maximum flash sync shutter speed.
1: On cameras that support slow synchro, varies by settings.
Auto Zoom for Sensor Size
EOS DIGITAL cameras have three sizes of image sensors, and the effective shooting angle of view of the attached lens varies depending on the size of the image. The Speedlite automatically recognizes the image sensor size of the EOS Digital camera and sets optimal flash coverage for the effective shooting angle of view of the lens in a focal length range of 24–200 mm.
Transmission of Color Temperature Information
This feature provides optimal white balance in flash photography by using color temperature information at the moment of firing, which is transmitted by the Speedlite to the EOS Digital camera. It is automatically enabled when camera white balance is set to 
, 
, or 
. Refer to the specifications in your camera's Instruction Manual to find out if it is compatible with this function.
AF-Assist Beam
When it is difficult to autofocus on the subject in low-light or when contrast is low during viewfinder shooting, the infrared AF-assist beam built into the flash automatically flashes to help autofocus.
The AF-assist beam supports 28 mm and longer focal lengths of the lens and its effective range (at 28 mm focal length) is approx. 0.6 - 10 m / 2.0 - 32.8 ft. at the center in the viewfinder and approx. 0.6 - 5 m / 2.0 - 16.4 ft. at the periphery (AF points other than the center AF point).
Caution
- Focusing with the AF-assist beam of an external Speedlite may be difficult when using a peripheral AF point on the camera, or when using wide-angle or telephoto lenses. In this case, use the center AF point or an AF point near the center.