For the bee-tracking system, we use a global shutter camera which means we can take extremely brief exposures, just capturing the time the flash is on.
Because there’s a delay between the trigger and the bulb actually firing (roughly 80\mu s) I use the PreDelay option to trigger the flash slightly earlier.
So to get an idea of the best combination of predelay and exposure time, I ran a grid search and found the mean of 3 photos at each combination.
Using just one Neewer TT560 flash (1/32 power).
It was quite noisy.
The scattering of dots on the right are, I think, due to delayed firing of the flash (by a few hundred microseconds). Similarly the dark dots are either when it didn’t fire, or these delayed events.
Given there are 4 flashes firing at once, I guess occasional failures like this don’t matter too much, but it would be nice to resolve.