[Ray-uk]

I have a similar setup that I use although mine is a little more elaborate in the fact that it has 2 light detectors so that I can measure both curtains independently.

However I measure from the point where the trace starts to rise to the point where it starts to fall. I find by doing this it eliminates the rise and fall times and is easier to make sense of the traces for the fast shutter speeds. I have shown my system drawn in green on one of your original diagrams below.

Attached Images