I was recently working on a project involving the use of 2nd curtain sync. The hard way, I figured out that the Canon EOS system only does 2nd curtain sync starting at 1/25s and slower. (You can read more of that on this blog post: At what speed 2nd curtain sync starts?
Then I compared it with the performance of the Pocket Wizard TT5 and its second curtain sync feature. The results with the PW TT5 are just great.
The timing of the PW’s is very precise, rendering results almost at the very end of the exposure. Here, Canon and PW 2nd curtain sync are compared side by side:
Note that above 1/25s the Canon reverts to 1st curtain sync. Clearly noticeable here by the drop going against gravity. On the frame taken at 1/25, the Canon sync captures the drop mid-flight, meaning that the flash was fired not at the end, but in the middle of the exposure. In the PW frame, the flash fired at the end of the exposure, as one would expect in 2nd curtain sync (with a small error margin, noticeable by the little trail under the drop).
Here’s the full set of the PW going up to the configured cutting point of 1/100 (configuration is done through the PW desktop app)
I must say that I’m impressed.