@rudi neat! I strongly suspect that the camera movement was slow compared with the “sparks” movement. Drift rather than jitter. If so, that would skew the *shape* of the burst rather than the *lines*. That is, if the burst was perfectly circular, but the camera drifting, the burst center would not be in the apparent center of the spark ends - if that makes sense.
@Rdyounger yes! Thanks for your comment. That’s what I was thinking too but couldn’t quite verbalize. Quick jitter would have been visible as a jagged bump in the light trails but slow drift distorts the curves in a way that still looks natural/expected for fireworks. Thanks for mentioning the drift vs jitter distinction — helpful.