Canon 80D Experience Manual page 19

Canon 80D Experience
Flash Firing: Enable so that the internal or external flash will function. If set for
Disable, the flash will only act as the AF-Assist Beam.
E-TTL II Metering: Set this for Evaluative.
Flash Sync. Speed in Av Mode: This setting determines the flash sync shutter
speed setting or range that will be selected by the camera when using the built-in
flash or an external flash while shooting in Aperture Priority (Av) mode (see
Figure 36 - right). The setting you choose really depends on your use and
experience with a flash, and whether or not you are using a tripod:
Auto will choose a wide range between 1/250 to 30 seconds, which may give you
very slow shutter speeds in certain situations which might be too long for hand-
held images.
1/250-1/60 sec. auto will keep it in a more reasonable range for hand holding, but
won't allow you to "drag the shutter" slower than 1/60 second. (Drag the shutter
means to use a slow shutter speed to let in more ambient light to better expose
the background, as the flash illuminates the subject.)
1/250 sec. (fixed) keeps it fixed at the camera's sync speed of 1/250 at all times,
which is the most "efficient" setting for external flash operation - meaning you
won't be using settings that may give similar lighting results but which are
causing your flash to work harder and inefficiently. The downside is you lose
control of this setting and the ability to drag your shutter.
recommend: Auto will obviously give you the widest shutter speed range, but will
require that you keep a close eye on the shutter speed to make sure it doesn't
get too slow. If you have less experience with flash or aren't certain you will
carefully keep your eye on the shutter speed, it would be wise to keep it set on
1/250-1/60 sec. auto. Remember, this setting only applies to Av Shooting Mode.
Figure 37 - Built-in Flash Settings menu (left), and External Flash Function Settings
(right). Both of these are sub-menus of the Flash Control menu.
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