If the zoom speed from the rocker is different (faster) than when using the zoom rocker on the joystick, you can try adjusting the "Z MIN SPD" option the controller:

1) Press the FUNCTION button on the joystick

2) Tap "PTZ INFO1"

3) On the first row, make sure "SPD WTH Z" is set to "ON"

4) Then change the "Z MIN SPD" option to the max level of "8"