Strobe questions from a new guy

Hello all,

I have been involved with photography for several years now, but the underwater landscape is a whole new ball game for me. I have been trying to decide between a new SnS Ys-01 or a set of two used Inon D180's with ULCS arms. So far I have been told that the Ys-01 would be a wiser choice because I cant be sure the D180's will sync with my Canon G10.

That dilemma aside, I am confused about the actual mechanics of a strobe. I am starting to understand that I can connect a strobe via fiber optic cable with one end attached to the strobe and the other to my Canon WP-DC28 housing. My confusion has worsened upon discovering the G10 doesn't preflash in manual mode. Does this mean that whatever brand I choose I will have to use the strobe in manual mode as well. And if so, what is the purpose of the fiber optic cable if not to meter the preflash? Do I use some kind of preflash cancel function and then the strobe will activate with the main flash?

And if I do go with the Ys-01, and end up having to use it in manual because the camera is lacking preflash, would that mean that I might as well go with the Ys-02 because it is strictly manual?

Any help would be greatly appreciated!

You can think of a strobe operating in manual mode as just a slave flash. That is to say, when the onboard strobe triggers, the light travels down the optical cord to the external strobe, which then triggers as soon as it "sees" the light. In manual mode, the communication is one way and just a simple "flash now" message.

With an optical connection and TTL, the onboard strobe sends out pre-flashes. The light from these pre-flashes travels down the optical cord to the external strobe. If the strobe is TTL aware and in the proper mode, it will mimic the pre-flash instead of triggering as a slave strobe (as it would in manual mode). The mimicked pre-flash illuminates your subject, which the camera then picks up in order to estimate the actual needed flash power. Now that the camera has calculated that estimate, it triggers the onboard strobe again for the real flash. When the light reaches the external strobe this time, it is able to mimic the length of the flash to set the appropriate power as well (more flash power just means it emits light for longer, not necessary more intensely). This all happens in such a very short interval that the human eye can't even really distinguish all the steps. This complexity leads to more circuitry in the strobe which leads to a higher price for a strobe that supports TTL.

So if your camera does not fire pre-flashes in manual mode, you're not going to get TTL over optical cables. In that case, you might as well save yourself some money to get the YS-02 instead of the YS-01. They're the same strobe except the YS-01 does TTL and costs more.

I pretty much always shoot manual personally even though my camera and strobes support TTL. It's not as difficult as it sounds. In cases where I'm shooting macro and really need a correct exposure (i.e., I won't get a second chance at the shot), I'll do TTL. But generally I find the lighting start to feel monotonous and flat when using TTL in macro and often completely over or underexposed when using TTL in wide angle.

Thank you for clarifying that, looks like I know the right choice now!