His trick is to start out of focus and go into focus during the exposure. This is pretty clever.
Thanks for the hint. I really wondered how he's doing it because none of my long-time exposures on fireworks look nearly like that.
It's an old trick - I've tried it a few times over the years - but if you can get the timing right the result, as above, are fantastic. I'm not sure mine ever work that well.
Next on "long exposure/focus changing" list of tricks are star trails with a discrete focus change once every 30 seconds (start in focus, then pull by x amount, wait, pull, wait, pull, wait ...)
I really need to get my hands on a good camera, because I want to try this.
Very pretty. ^_^