When I shot them (on film), I used a tripod, ISO 100 (the lower, the better to get the sky black), f/8, and for shutter speed (I think) either 'B' and a cable release or else something fairly long, like 8 seconds. You want a long exposure to get a "flower", rather than a circle of dots. Open the shutter just as you see the rocket going up.
Of course, which lens depends on how close / how far you are from the show. But at f/8, anything in your sig should work. Unfortunately, modern AF lenses tend to focus past infinity, which makes it harder to just focus manually at infinity and leave it.
I never graduated to the advanced stuff, where you have something interesting illuminated (and properly exposed) in the foreground, with fireworks and black sky in the background.
Last edited by THoog; 06-28-2016 at 12:48 PM.