Chris Ross
Contributor
It sounds like if you stay wide you are OK, albeit with a slow shutter speed. I think the solution may involve adjusting you shooting style if you are doing wide angle stay at the widest and try and get closer. Only use the zoomed in settings for macro subjects where you get 100% illumination from the flash? At least in darker waters. You can always shoot at f2 - it is about equivalent to f11 on full frame.