5. Use the Aperture to Control Exposure
If you're new to manual mode, you might feel overwhelmed by all the settings--ISO, shutter speed, and aperture—and not know where to start. Here's what you should do: Set the ISO at 100 (or its lowest value) and the shutter speed at about 1 or 2 seconds. Then take some pictures, varying the aperture setting. The smaller the f-number you dial in, the brighter your fireworks will be. If your photos are getting overexposed, increase the f-number. If the photos are too dark, shoot at a smaller f-number. This scene is the result of a 4-second exposure at f/8.