OK, here’s what you need:
A camera, with a bulb setting.
Remote shutter release
Here’s how you do it (based on my 2013 settings):
Find a spot where you can see clearly. Last year I took pictures on three different nights, and I can tell you this, over the bay with a long lens sounds like a good plan, but your lens is probably not actually long enough. My 250mm wasn’t good enough to shoot anything more than about 2 miles away, and you may not realize it but the bay is at most points, wider than that. I found the absolute best pictures I took were from India Point Park for the East Providence fireworks show. Shooting for McCoy Stadium is tough if you’re not really high up or already in the park.
You’re not going to get every burst, so don’t get upset if you miss some. Even if they were really really awesome. Because there are more awesome ones coming. In fact, I use the first 3-4 bursts to set my focus in live view, then lock it down. Oh and focus…
MANUAL FOCUS. The camera doesn’t know how to focus, especially when you’re starting in the dark.
What mode should I be in? MANUAL Mode. (The one with the M.) You’re going to have to with Bulb anyway. And don’t leave the ISO in auto either, set that at 100-200. No more than that, or it’ll just make the sky really noisy and distracting.
Hold the shutter open from as early as you want (whether or not to catch the mortar trail is up to you) through the whole burst. Why so long? Because…
Shoot at a very high F-stop. I shoot mine at f/18 or f/22, it keeps the blacks black and the brights get through just fine. Plus you will have no issue with depth of field that way. Some people will shoot at f/8 or f/13 justifying that they’re already shooting in the dark, but I don’t think that helps. You end up with more of the ambient light from the reflections off the smoke. Maybe you want that, then go for it.
Have a friend around. Or several. Last year I shot once from the roof of a store, which I couldn’t use the shots because the fireworks weren’t as high in the air as I had hoped, and ended up with the power lines cutting through all of them. And I was alone up there and after a while it got kinda boring. When I shot at India Point Park, I had my friends Jesse and Meg with me, and they not only kept me company but Meg and their daughter sat on the ground in front of my tripod which kept people from walking in front of it.
Oh yeah, the TRIPOD. It’s kind of a big deal. Stability. Tied right in with that is the remote shutter release, and you’ve got a camera that isn’t moving. You won’t be moving it by shooting handheld, and you won’t even vibrate the camera when you push the shutter wince the remote release will take that out of the equation.
Angle: whatever fits, last year it was right around 50mm for my India Point Park shots.
Aperture: Smaller is better. f/18 is where I liked it. (Not f/1.8)
Remote (Cable) shutter release: Good idea.
Portrait/landscape: Mix it up.
Time: Bulb, experiment, but from just before the mortar to the end of the burst is great.
ISO: 100-200, NOT AUTO.