I have an issue where it seems like if I take reapeated shots in quick sucession, the camera blacks out and shut down.
I suspect it is because the water is a little bit chilly, about 5dgrees centigrade, and I take flash shots in quick sucession. After 3-4 shots, the last shot does not come up in review-mode, but the screen black out once, and then the camera comes up again in camera mode but is unresponsive and then blacks out again. At this point I flip it on and off again, and it is ok.
So i suspect that the battery does not deliver enough power when recharging the strobe and the voltage drops so the camera shuts down. However, to contradict that, no battery symbol shows, and I am not shooting in TTL mode, but 1/64 manual mode which should conserve power to some extent. The batteries (both) are originals, only a couple of years old maximum.