In a previous post I talked about high-key lighting. The opposite of this type of lighting is Low-key light. Low-key has a more dramatic effect. If you want a more dramatic portrait, you can choose to work with a low-key lighting setup.
According to Wikipedia:
Low-key lighting requires only one key light, optionally controlled with a fill light or a simple reflector.
Low key light accentuates the contours of an object by throwing areas into shade while a fill light or reflector may illuminate the shadow areas to control contrast. The relative strength of key-to-fill, known as the lighting ratio, can be measured using a light meter. Low key lighting has a higher lighting ratio, e.g. 8:1, than high key lighting, which can approach 1:1.low-key
Low Key photographs generally have a darker tone and contain a lot of dark areas. You can use a single light to light your subject. The best effect is reached when you highlight the contour lines of your subject. You can use a fill light or reflector to light the front of your subject. But make sure the ratio is ok. A 1:1 ratio will make your image too bright for low key. Also a frontally lighting your subject will not get you the desired effect. For low-key lighting you don’t want to light your subject evenly. You’ll want to light certain parts to create a dramatic effect.
Here a lighting setup I used a couple of times to get a low key effect. To make it a bit easier on yourself, you should use a dark background, When using a lighter background, you should make sure the subject is placed far enough from the background and the light is relatively close to the subject.
In general this light will have a dark mood to it and because of the contrast with light and dark, you will see more ‘imperfect’ features of your subject. For instance if you’re shooting somebody who has some wrinkles and does not want them to be emphasized in the photo, you’d be better off choosing another lighting technique.