5) Settings: Use a slow shutter speed with a low ISO.
As mentioned above, fireworks look best with a slow shutter speed so that some of the movement of the explosion is caught on the camera’s sensor. To select a slow shutter speed, shoot in shutter priority (Tv or S mode) on your mode dial. A good shutter speed to start with is somewhere in the ball park of about 5 seconds – plenty of time to capture the movement of the fireworks in the sky, and perhaps form a cluster of several fireworks all adding in together. Generally LOW ISO’s go with SLOW photos, so select a low ISO. ISO 100 is probably a good starting point.
It’s worth paying attention to key buildings and structures in your scene. Remembering your ‘Rule of Thirds’, if it’s a city fireworks display, try and have a prominent building somewhere on one ‘vertical third’ line. If it’s a bridge (eg the Sydney Harbour Bridge) think about having this on a horizontal third line. Also pay attention to your foreground. Sometimes trees framing up your shot look great silhouetted against the bright fireworks.
In Tv (or S) mode, you select the desired shutter speed and the camera automatically works out the aperture (f/number) for you to achieve a correctly exposed photo. As the camera works out the aperture, you don’t need to worry too much about this. Just double check, though, that your f/number isn’t blinking or flashing at you. If your f/number is blinking, the camera is warning you that the resulting photo won’t be correctly exposed. If the f/number blinking at you is a big number (eg f/22) then it’s warning you that your resulting photo will be over exposed. In this case you’ll just need to select a slightly shorter shutter speed. If the f/number blinking at you is a small f/number (eg f/4) then your camera is warning you that the resulting photo will be too dark, so either bump up the ISO or select a longer photo to let in more light to rectify this. If your f/number isn’t blinking then you’re good to go!
It’s a good idea to do a test shot before the fireworks start to see if you’re happy with your composition and the resulting exposure of the photo. Fireworks are obviously bright and introduce more light into the scene so once they begin, keep checking your resulting photos on the back of your LCD screen (and also double check the f/number isn’t blinking at you). Remember you can always brighten/darken the photo by adjusting your Exposure Compensation (+ for brighter).
More advanced users may like to even switch over into Manual Mode (rather than Tv or S) and dial in these same settings to lock-in correct exposure for the scene so that when these random explosions of light start going off in the sky, the camera doesn’t try to compensate by changing settings from one shot to the next. This isn’t usually much of a drama though, so I wouldn’t suggest you worry about going into Manual Mode unless you’re finding your images are varying wildly in their exposure from one to the next.