Yongnuo Speedlite YN468-II, User Manual, Page: 7 / 12

6. S1/S2 Mode
Press the [MODE] button, then the flash will enter S1/S2 mode.
These modes are applicable for slave flash in order to create many
light effects. They are respectively applicable for manual flash
environment and TLT flash environment.
When the flash is in S1 mode, it will work with the first work of
the master flash synchronously, with the result consistent with the
use of radio slave. To use this mode correctly, the master flash
should be set at manual flash and the TTL flash system with
preflight function and the red-reduction function with multiple
flashes should not be used.
S2 mode is similar to S1 mode, but it can support the master flash
in TTL mode. In particular, if S1 mode cannot have correct and
synchronous flash with the inbuilt flash, you can try to use S2
mode.
7. Menu Access of Camera (only compatible with Canon
ETTL camera system)
On the Canon camera
supporting ETTL, you can
switch flash mode via the
camera menu. With the
setting function of the
external flash function in the
flash control menu, you can
switch between the TTL
mode and the manual flash mode; in addition, on such menu, you
may also set front and rear curtain synchronization, and set
manual flash output with 1/3ev step length.
8. Test Flash
Whether in any mode, you can press PILOT button to test if the
flash light flashes normally.
In M/S1/S2 mode, press the PILOT button and the flash light will
send light with different luminance as per levels of output power
selected.
9. Power-saving Function
In TTL/M/MULTI mode, if idle for about 30min, the flash will
power off automatically.
In S1/S2 mode, if idle for 60min, the flash will power off
automatically.