Ok, set the flash to Manual 2, not TTL. (Oh, you do have the strobe set to "Slave" right?) The FO cable only triggers the slave sensor on the flash, it won't have TTL control. Don't use Auto on the camera. Not to be a "purist" or anything, it just won't allow for easy control in the situation you are using it in. When you use the G-10 on Manual you need to be able to select between aperture and shutter speeds.
You use the "jump" button (just above and to right of the control wheel/rocker switch area) to go between f/stop & shutter speed selection in Manual mode. To adjust either one (once selected using the jump button) you would normally use the control wheel when shooting w/out the housing. I don't know--does the FIX housing give you a way to use the camera control wheel? My Canon housing doesn't but there is a simple way around that. (If you can't easily adjust f/stops w/ your housing let me know.)
I know, sounds complicated but when you try it a time or 2, it isn't. Use the light level control (output adjustment) on the YS110A too, don't just leave it on "full". Beween f/stops and flash output adjustment you can easily adjust things for great exposures. Fiddle with it a bit, ISO 80 or 100 is fine. What was going on was that on Auto, the camera had no way of knowing the strobe was going to throw a big bucket of light at things from the strobe when you hit the shutter release, so it was adjusting for the dimmer light that was present--a whole lot less light than when the strobe is added. f/5.6 (or f/8) can work fine, especially for macro, but not the way you were set up.
Do a bit of shooting topside before you dive again (maybe not a bunch though, I'm told the stobe can heat up if used excessively aboove water). You won't find yourself changing settings all that much UW, so once you are dialed in it gets easy. Give a yell if this makes less sense than I think...
Or if it's better to have someone show you, sounds like Scottfiji made a swell offer! //ww
