Canon Speedlite 470EX-AI Instruction Manual page 60

General Cautions for AI.B Full-Auto Shooting and AI.B Semi-Auto
Shooting
If the camera is held at too steep an angle after a change of orientation
(position), automatic bounce angle correction may not be performed. In
addition, automatic bounce angle correction will not be performed when
the change of orientation makes it impossible to reset to the stored
bounce angle.
Since the turning angle of the flash head is indicated in 5° increments,
the angle may be displayed with a margin of error to an extent of 5°
(before and after the automatic correction) such as when the bounce
angle is automatically corrected.
When the flash settings are cleared during AI.B full-auto shooting or AI.B
semi-auto shooting (p.40), the bounce angle stored (registered) in the
Speedlite is cleared. Therefore, pressing the shutter button halfway
returns the flash head to the forward-facing position.
AI bounce flash photography cannot be performed with the release
button on a remote controller or the touch operation of the camera (not
supported).
Notes for AI.B Full-Auto Shooting and AI.B Semi-Auto Shooting
When using an EOS DIGITAL camera released in and after the second half
of 2017 (p.46), "AI_b" is displayed on the camera's viewfinder as well as the
LCD panel, and [AI BOUNCE] is displayed on the LCD monitor if the flash
head moves in the following three cases, 1, 2, or 3.
1. When the <X> button or the like is pressed for distance measurement
operation during AI.B full-auto shooting (with the camera's metering timer
active).
2. When bounce angle correction is performed by double-clicking the
shutter button during AI.B full-auto shooting or AI.B semi-auto shooting.
3. When the position of the flash head is (inadvertently) moved by pressing
the shutter button halfway to automatically correct the bounce angle after
distance measurement operation during AI.B full-auto shooting or after
the bounce angle was stored (registered) in the Speedlite during AI.B
semi-auto shooting.
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