Night portraiture can be tricky because there are a lot of things to think about, and exposure, flash, camera shake, and colour balance are just the tip of the iceberg. Most modern cameras have settings to help you take great nighttime shots, but why do some turn out looking great while others are a blurry or bright mess?
To better understand what’s going on inside the camera, we headed out with a Nikon D90 with a 28mm, f/2.8 lens to try to take the best night portrait shot possible. There’s always more than one method, so we tried several techniques.
Daytime exposure with the flash turned on
If you use a camera’s daytime settings at night, you’ll end up with an underexposed image. The obvious solution is to turn on the flash. In manual mode, when you turn the flash on, it will go off for every shot, regardless of whether it’s needed in the frame.
Posing near San Francisco City Hall for nighttime shots taken with a Nikon D90 and a 28mm, f/2.8 lens. The bad photo (top) uses a daytime exposure with flash at ISO 320 at f/2.8, with a shutter speed of 1/200 and flash on TTL. The good picture (bottom) has a manual setting of ISO 320 at f/2.8, with a shutter speed of 1/20 and the flash on TTL. The shutter speed made all the difference
Through-the-lens (TTL) is the default flash setting for most cameras. It examines the scene before deciding how strong the flash needs to be. This usually means that your foreground will be properly lit, but the camera will light the background based on the exposure settings you set previously.
Auto mode will take a clean, clear photo of your subject, but it won’t pay any attention to the background. While it may include data from the whole scene, its priority is to expose the point of focus. Auto mode works fine when the subject and background are in the same light, or where the point of focus is what’s important in the frame, but not for a nighttime portrait in front of, for example, a landmark.
Night portrait mode
The night setting on your camera will slow down the shutter speed drastically and set the flash to auto plus slow sync – this tells the camera that you’re taking a slow-exposure photo with flash. The idea behind these settings is that, although the shutter speed is very slow, the burst of the flash will freeze the subject. While this photo will correctly expose both the background and the subject, the colour balance may be too warm. Also, the shutter speed will be so slow that if your subject moves even slightly, there will be ghosting. Another possible problem with such a shot is the starbursts coming from streetlamps – a byproduct of the slow shutter speed.
A good rule of thumb for manual flash photography is to expose the background, set your flash for TTL and then make the shutter speed faster by two stops. In this case, we instead made the ISO lower, though this achieved the same goal of allowing enough light into the frame to expose the background, yet not enough to blow out the foreground. Because the shutter speed was slightly higher than for the night portrait mode, we were able to avoid starbursts, and the lower ISO minimised noise.