I'm very new to using an underwater strobe and don't really understand how a TTL system works using a fiber optic connection. I've been watching youtube videos explaining TTL in normal cameras connected via a hotshoe with an electronic connection and kind of understand that the camera fires a pre-flash to determine how much power it needs for the main flash. But how does this work with a simple optical trigger? If the camera uses its own pre-flash to trigger a pre-flash in the strobe and then provides corrects the main flash power, how is this information conveyed via the fiber optic from the camera to the strobe? To clarify, does the strobe vary its power according to the amount of light carried via the fiber optic cable?
I have a Sony RX100M4 connected to an INON Z-240 (unfortunately there's no manual) via optic cable.
Does anyone know if the RX100 uses a preflash when I use the fill flash? Should I put the Advanced Cancel Circuit Switch up or down on the Inon Z-240?
Any help would be very appreciated.