Typically, noise/grain is not a problem in this type of image. We recommend that you use ISO 200, or 400. The important point is that you don’t need a very fast ISO; in fact super-fast ISOs may overexpose the firework display. Very slow ISOs – for example, ISO 100 – may not be sensitive enough to capture the display. (Remember, while your shutter will be open for a second or two or more, the actual appearance of the “rockets red glare” will last only a fraction of a second in any one place.)
Since many of today’s digital SLRs offer good results at high ISOs such as 800, 1600 and 3200, why not use a faster ISO? The answer is simple – you don’t need to. You want a long exposure time, and as we’ve mentioned elsewhere, the bursts of the exploding fireworks are bright enough to etch themselves onto low ISO sensor settings such as 200 or 400, even with a medium-size aperture setting. A higher ISO would just run the risk of overexposed washed out colors. We also suggest, because of the brightness of the fireworks vs. the dark night sky, that you avoid using the “Auto ISO” setting, one that we don’t use much anyway.
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