Canon YJ12X6.5B IRS-A - Manual (Page 27)

How to use the shuttle-shot
When holding down the ShtI button,
the zoom moves toward the shuttle
memory position at the maximum
speed, and stops at the shuttle
memory position (preset zoom
position).
So long as the ShtI button is held
down, the zoom stays at the shuttle
memory position.
How to return to the original position
The original position is not changed so long as the zoom operation is only performed
using the ShtI button.
The zoom position obtained by manual or any servo zoom operations other than
the ShtI button, will automatically become the new original position for the next
shuttle-shot operation.
^ (NOTE):
Since operation with the ShtI button is given priority, operation cannot
be performed with the zoom seesaw switch while the ShtI button is held
down.
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