The placement of your light source matches specifically with the face position of your subject.
The camera placement won't have any effect to the lighting pattern, even when you shift the camera around, the manner the light illuminates on the subject's face stays constant. Should the subject moves and we want to preserve a similar lighting pattern on the subject's face, the light needs to move in relation to the face too.
In short lighting, the camera's location sees the darker section of the face primary as it slowly becomes lighter closer to the lit part. This lighting style is favored because of the slimming appearance it produces on most faces.
Except when the subject's face is very long and narrow, short lighting can more often than not enhance the appearance of the subject.
Broad lighting is the reverse of short lighting where the camera sees the illuminated part of the face just before slowly fading to the shadows at the back. Broad lighting emphasizes the face straight to the viewer and usually portrays a lighter and cheery individuality than a mysterious short-lit portrait.
This lighting pattern is effective with subjects with narrow or long faces or people who want to conceal facial flaws may be lessened.
The split light 'halfs' the subject's face right in the center where the nose bridge and forehead vertical rest. The split light can be a very striking light pattern best suited for male subjects.
It is one of the best lighting pattern for featuring detailed facial features such as beards, wrinkles, etc.
You can accomplish the split light pattern by placing the light 90-degrees to the side of the subject.
The level of your light immediately impacts the direction of your shadows that appear on your subjects' face. As you adjust the position of your key light, features such as cheekbones, nose size, eye socket depth, catch lights in the eyes, all transform significantly.
If you place the light close to the same height of your subject's head, the lighting gets flatter and the shadows seem more linear (left-right/up-down). As you shift the light to in-between angles, you can immediately see every angular characteristic of the face becoming more defined and depth is produced by the shadows.
Subject Placement in Available Light Conditions
The light placement described above is applicable whether you're utilizing a portable light source such as a desk light fixture or studio flash, or natural sunlight. The main difference between utilizing the artificial portable light vs. natural daylight would be the latter needs you to alter the subject's position relative to the fixed sunlight as compared to shifting the light source around the subject.
Notice that nearly all light patterns have the light height around the same level as your subject as the sun seldom move beneath your feet level. Normally, your key light will often be higher than your subject.