i have this old speedlight and wonder what is the mode that has the 3 flash symbols? it is not the A, M and TTL. after switching to that mode, there is something like 1-10 Hz, 3-9Hz, what are these settings for?
A = Automatic Sensor (Non TTL) light output is measured with the sensor on front of the flash rather than via the sensor in the camera body.
M = Manual - User sets up the flash to suit their requirements.
TTL - Through the Lens flash control
SSS - Flash repeat function. A strobe function that is used to put the flash in to multiple firing mode that gives X flashes per second. User selects the number of flashes per second.