How to take night photographs with flash?

This post is written with the Canon user in mind.

Normally, if you want to snap a picture of someone at night, you will use the flash, set your camera to the green box or P mode and fire away. All is fine, till you review the picture. The background is so totally blacked out and only the subject is well-lit. What happened?

Well, in the Canon system, if you are using the green box or the P mode, the camera will assume that you are using ONLY the flash as the main light source, and will set the minimum shutter speed to 1/60s to avoid camera shake. Also depending on the camera, ISO will be set automatically (or not). Anyway, since the built-in flash of many cameras have very limited power, the amount of light generated from the flash is not enough to light up the entire room or background. It can only reach far enough to light up your main subject. That is why you get what you get.

The smarter way would be to switch to some manual modes. You can use either Av or Tv or M mode. In these modes, the camera will assume that you are using the ambient light as the main light source, and the flash as a fill-in light only. This means that the camera's light meter will set the aperture and shutter speed to expose for the room or background correctly. Typically, for night shots, I like to use Tv mode set to 1/25s or 1/30s, ISO800 or ISO1600, and fill-in flash. This achieves several things: firstly, the shutter speed is slower than 1/60s yet not too slow to induce camera shake; secondly, the ambient light is well registered in the camera by using high ISO; thirdly, by filling in with flash, I can fill in the shadows in my main subject and also catch some sparkle reflection in their eyes.

Alternatively, I also use Av mode sometimes, but I have to keep my eye on the shutter speed to ensure that no camera shake is induced. Typically I like to underexpose by -1/3 or -2/3 and correct the levels in post processing later.

If you have a separate flashgun (e.g. Speedlite 430EX), you can do some bounce moves and have better control over the direction and size of your light source. I am now learning how to use a bounce card to achieve better flash results. I point my flash gun to the ceiling, attach a curved piece of white paper to the back of the flashgun so that the reflected light is diffused forward, while the main flash strobe is bounced on the ceiling to create a soft effect. This can work 80% of the time, but of course the photographer must be mindful to ensure that the ceiling is not too low (overpowering flash) or too high (wasted flash power).

Anyway, those are the tips I can think of. Basically, don't use the green box and P mode because that will fix your shutter speed to 1/60s or faster, and that is just too fast for the camera to capture any ambient light from the room or background.