EQUIPMENT AND EXPOSURESWhether you're working with a point-and-shoot or a DSLR, the first ingredient for night photography is manual control. You don't need to be a master of exposure, but you should have a camera that allows you to adjust shutter speed and aperture. Use your lowest ISO (either 50 or 100), and set your camera to manual mode. Then you can begin modifying the aperture and shutter speed to create the effect you're after.
In most cases, you want to produce a deliberately long exposure, so a small aperture (such as ƒ/16, ƒ/22 or ƒ/32) will help you create shutter speeds in low light that are in excess of 5, 10 or even 30 seconds long. These long shutter speeds allow for any moving lights in your scene, like fireworks or stars, to move across the sensor and create a beautiful streak of light.
FIREWORKSPhotographing fireworks is a rare opportunity, so it's important to make the most of your efforts. Start with a camera locked down on a tripod and a cable release, and choose a composition that allows you to photograph the fireworks-filled sky, as well as some context. Trees, buildings or people in the foreground are ideal to set the scene and provide scale.
If at all possible, arrive early to set up while it's still light; it's easier to see your camera settings and to choose a composition. No matter how early you arrive, though, you're bound to have to make some adjustments once the show starts. Make them quickly because the beginning of the show is the best time to shoot: The sky isn't yet filled with smoke, and any residual sunset glow will provide a deep blue background.
Start with a low ISO of 50 or 100 and an aperture in the middle range of ƒ/8, ƒ/11 or ƒ/16. Focusing at infinity ensures your fireworks are sharp, and setting the lens to manual focus stops the AF system from hunting in the dark. A smaller aperture can increase depth of field and lengthen exposures. This is good on two fronts, as more depth of field means you can ensure compositional elements are sharp, too, and longer exposures mean better motion blurs, which means better-looking fireworks. But there's a downside to longer exposures. Too many fireworks going off in a single frame can muddy a scene, so rely on experimentation verified via LCD to quickly hone in on an ideal exposure—likely somewhere from a few seconds to 10 or more to produce a good amount of blur without washing out the colors.
NIGHT PORTRAITSPhotographing a person at night (or in very low light) is the one time you can break the typical night photography rules: You need a flash, but you don't need a tripod. Off-camera flash is ideal, but even a point-and-shoot with an on-camera flash will work.
You may say, "I just use my camera's Night Portrait scene mode to make night portraits." That's fine, but knowing how to achieve that look without auto assistance will make you a more empowered photographer. And it can help you make better night portraits when Night Portrait mode falls short.