altura PRO SERIES User Manual page 15

7. S1/S2 Mode
Slave1 & Slave2 (S1/S2) modes are mostly used
for off-camera flash units. This mode uses the
wireless trigger sensor to fire when sensing other
flashes go off. Use S1 when your built-in camera
flash, or master flash, is set to "manual" mode.
Use S2 when your built-in camera flash, or
2
master flash, is set to TTL mode. Refer to "M"
mode to adjust S1/S2 settings. Press the <SET>
button to select different settings & the
<ARROW> keys to adjust them when they are
flashing.