Technical

INTRO TO PORTRAIT LIGHTING

Good lighting is a critical component of portraiture. It's also easily identifiable even by the casual observer. However, despite this apparent simplicity, knowing how to use light to achieve a desired look requires a much deeper understanding. This introductory tutorial discusses the most basic scenario: portraits with one light source. Subsequent tutorials will discuss setups with multiple lights, but the same principles discussed here still apply.

OVERVIEW: ONE LIGHT SOURCE

The primary source of subject illumination is usually called the main or key light. Although additional lights may be added to enhance a portrait, key lighting is usually performed independently. This is great news for those trying to learn portrait lighting, because it means one can ease into the process one light at a time. If and when you decide to include additional lights, everything learned here will still apply.

Only one trait controls the appearance of light on a subject: its distribution*. Even though some lighting may seem to have a magical quality, it's ultimately nothing more than this. However, for a given light source, we can separate this out into two more easily manageable characteristics:

1. Direction, which controls the location of shadows and highlights on the subject, and
2. Apparent Size, which controls the appearance of these shadows and highlights.

SIZE: HARD VS. SOFT LIGHT

We'll start with apparent size, since this is perhaps the most common cause of poor portrait lighting. When photographers describe light as being "hard" or "soft," or use the term "light quality," they're actually just referring to the size of the light source:

		Harder Light	Softer Light
Light Size	→	Smaller	Larger
Shadows/Highlights	→	Abrupt	Gradual
Types of Sunlight	→	Direct	Overcast, Shade
Types of Flash	→	Direct	Bounced, Diffuse

• Diffuser. Place a larger translucent object between your subject and the light source. This might include using a lamp shade, or hanging a white sheet or curtain over an open window that receives direct light.
• Bouncing & Reflecting. Place your subject so that they receive only bounced or reflected light. This might include moving them a little farther from an open window (just outside the direct rays), or aiming your flash at a nearby wall or ceiling

DISTANCE & APPARENT LIGHT SIZE

At this point you've perhaps been slightly misled: it's not really the physical size of the light source that matters — just its apparent size relative to the subject.

Closer light sources become softer, because this light strikes the subject from a broader range of angles — even if the light itself remains unchanged. Similarly, the opposite is also true: direct sunshine is hard light even though the sun is physically enormous. The sun is just so distant that its light reaches us from roughly one direction.

DIRECTION: SENSE OF DEPTH & REMBRANDT LIGHTING

Finding the right lighting direction requires the photographer to strike a balance between several potentially competing considerations. Typically, this includes both (i) portraying a sense of depth and (ii) depicting facial features as attractively as possible.

(i) Sense of Depth. Creating the appearance of depth is a key part of capturing realistic-looking portraits. However, our sense of depth doesn't work very well unless light is striking our subject from the right direction. For example, a sphere is a reasonable approximation for the shape of our heads, and it only appears three-dimensional when light strikes it from a front upper side:

(ii) Appearance of Facial Features. In addition to the head as a whole, each facial feature also has its own shadows and highlights — all of which deserve special consideration. This might include avoiding making the nose appear larger by having it cast a long shadow, or making the subject appear tired by portraying shadows underneath their eyes. Upper side lighting could cause these and other undesirable effects if not carefully positioned.

• Too Big (Tall or Wide). This means the light is too close to the subject's forward direction, and likely isn't creating a sufficient appearance of depth since most shadows are hidden from the camera's perspective.
• Too Narrow. This means the light is too far to the side of the subject, and could cause the nose to appear bigger by having it cast a longer shadow, along with potentially leaving a substantial portion of the face in shadows. However, this is perhaps the least adhered to of all the key triangle guidelines.
• Too Short. This means that the light is too high or low, and is likely causing shadows underneath the eyes or a lack of shadow definition along the jaw line, respectively. Lighting from below is often used for unsightly creatures in movies, or to create a frightening face when telling a scary story (by holding a flashlight under the face).

CONCLUSIONS & FURTHER READING

In general, the goal of portrait lighting is to achieve softer light. This makes a subject's features appear smooth and gradual, and makes skin texture appear softer. Achieving softer light requires making the apparent size of the light source bigger. This can be done by either (i) moving the light closer, (ii) increasing its physical size, or (iii) bouncing this light off of or diffusing it through other objects.

However, the choice of lighting direction is definitely more subjective than that of hard or soft light. Even so, two lighting orientations are usually considered undesirable: lighting from underneath and directly from the front. The former isn't something that appears natural, and the latter destroys the portrait's sense of depth. In any case, one generally wants to portray their subject in a flattering light, but each subject is unique and may require a different treatment.