Here are some suggestions that I follow when taking pictures of fireworks. Hope they will be useful.
1. First of all select a good spot. Picture of just a firework in the sky won't look artistic. You need something else to accompany it: castle, bridge, cathedral, some famous landmark or just nice houses on the riverside.
2. Come prepared. Tripod and remote control (or shutter release) are a must.
3. The first couple of shots should be test ones. Just to understand the time between firework shots and what time do you need to have the picture right (not over and not underexposed).
4. Then the process is easy. As soon as the firework comes out click on the remote control and wait the time calculated on the previous step. Looking at the result you can then slightly adjust the time.
5. The picture will look best if you start taking it when firework is going up and opening and stop it before it will be going down.
And here are some photos from Moscow that I took using this technique:
05-03-13, 02:55 PM
