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Portrait Photography Lighting

An Article on Lighting by Steve Barnes

Portrait Photography Lighting

Portrait Photography Lighting - Light is really the raw material for a photographer. Much as the sculptor works with stone and the painter works with paint, the photographer works with light. This analogy is not quite so precise though, because as the painter and sculptor work with tangible material substances, a photographer works with a form of "energy".

By understanding the behaviour of this energy that we call light, you form a foundation for your success as a portrait photographer.

A painter might not need to know the chemical and physical properties of each and every component of her oils or paints. However, she must understand how to blend the different colours.

Also, how the paints behave as she applies them to the canvas takes practice, experience and knowledge.

A sculptor or painter must gain masterful insight into the physical behaviour of the raw materials of their chosen arts. So must the portrait photographer gain a keen and polished understanding of the behaviour of light.

The first prerequisite for any photography is some form of light being emitted from a source. Think about it, without light, photography is absolutely impossible.

The light you use may be emitted from a natural source, like the sun, or from any artificial source such as speedlights, strobes or a constant light source.

Portrait Photography Lighting - Strobes

In 1931, Harold Edgerton, an electrical engineer from MIT, developed the strobe for use in still photography.

Today, the strobe is easily the most used light source in the portrait photographer's studio. Some advantages of strobe lighting for portrait and studio photography include;

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    Reasonably precise control of light intensity and light color temperature
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    Low heat generation compared to a constant light source
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    And low power consumption for the amount of light output

Probably the most important aspect of light to the portrait photographer is the light's actual intensity or brightness.

There are a few ways of controlling the intensity of light striking the portrait or subject. In the studio, the power supply for many modern strobes may be manually adjusted.

The strobes can be positioned further away from the subject. If outdoors, you may take advantage of cloud cover or the overhang of a tree or building. You can even use the time of day to control the intensity of the available light on the subject.

Portrait Photography Lighting - Controlling Light

These methods are effective for controlling the average or overall light intensity on your composition. Many devices have now been developed to control the relative intensities of light on specific areas within a photo or composition.

Devices such as:

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    Gobos
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    Scrims
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    Snoots
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    Barn doors
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    Grid spots

...are commonly used to partially direct, block or otherwise control the light intensities within a particular composition.

Portrait Photography Lighting - Colour Temperature

Another property of light which has great importance to the portrait photographer is the lights' colour temperature.

"Pure" white light is the result of an equally balanced mixture of the three primary colours being:

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    Red
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    Green
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    Blue

In certain lighting conditions (e.g. cloudy versus bright sun), the proportions of the color mixture can vary. Normally, our brain will automatically compensate for this and you will not notice the difference in "temperature" as you leave one lighting situation and enter another.

Film or sensors cannot make the same automatic compensation. So differences in colour temperature must be manually adjusted by the photographer.

Colour temperatures of various light conditions are commonly stated in degrees Kelvin. There are (if you still use them) three standard colour temperature rated films that are commonly used by photographers.

"Daylight" film is manufactured to be exposed by 5500K light. "Indoor" film is made to be exposed by 3400K light. 3200K light is used for professional "indoor" film.

For a larger degree of control over the white balance setting when using film, colour correction filters are normally used. Most, if not all Digital SLR cameras now have their own, in-built white balance adjustment. This is for you to electronically and manually compensate for changing colour temperatures in various light conditions that you may come across.

With digital photography, the colour temperature can easily and quickly be corrected in Photoshop. This is made easier by shooting in RAW format.

Portrait Photography Lighting - Contrast

A third, important property of light for the portrait photographer is contrast.

A light source will have a high contrast if its rays all hit the subject at approximately the same angle or direction. A diffused light source has low contrast because its rays hit the subject from many different angles.

High contrast light sources will produce shadows with a hard, highly visible edge. Low contrast light sources produce more aesthetically pleasing shadows with a soft edge.

This is because when using a high contrast light source, where its rays all approach the subject from approximately the same angle, no light enters the edge of the shadow created and the shadow's edge will remain distinct.

A light source's contrast is basically determined by the size and intensity of the light source and its distance from the subject.

For example, the sun on a clear day is relatively small in our sky. Therefore it is a high contrast light source which produces a hard edged shadow. On a cloudy day, the diffused light from the same sun is spread out and more flattering.

Like a studio set up, the entire sky becomes a lower contrast light source, giving very soft edged shadows, good for portraits.

Portrait Photography Lighting - The Behaviour of Light

In the photography studio, we have many light modifiers available to use, so as to control the size of the light source and so control the level of its contrast. For any given size of any light source, as it is positioned further and further away from the subject we can see that it effectively becomes much smaller, thereby yielding much higher levels of contrast, albeit lower with lower intensity.

Light always acts on any subject it strikes. This much may be obvious but every subject also reacts on any light that strikes it.

A subject can act on light hitting it in three distinct and different ways;

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    Refraction
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    Absorption
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    And reflection

Refraction, Absorption and Reflection

Refraction is the bending or redirection of light waves as they pass through any transparent material such as water or glass. In fact, the refractive properties of glass are what are manipulated within photographic lenses, in order to focus an image onto the film (or digital imaging sensor).

Absorption is the process where certain materials convert light energy into another form of energy (usually heat or temperature). The absorptive properties of a black-painted, foam core board can be used by a photographer to selectively "subtract" or reduce light, so that it does not bounce itself around the studio in an undesirable and unflattering way.

Reflection. Of the three ways a subject may act on the light striking it, reflection is (for most) the most important to the photographer.

Reflection is a quick and abrupt change in the direction of light waves that strike the surface of any subject. In direct reflection, the light rays will bounce from a smooth surface at the same angle at which they hit. The actual intensity of the direct reflection will mirror the intensity of the light source.

Glare, like that seen on the surface of a body of water, is known as a polarized direct reflection.

Unlike direct reflection though, "glare reflection" will always have a lower intensity than the light source which produces it. Glare reflection can be controlled or mostly eliminated by using a polarizing or polarizer filter.

Portrait Photography Lighting - Diffusing

Diffuse reflections normally occur when light from a source is equally reflected in all directions by the surface onto which it strikes. So, in theory, diffuse reflections are the same intensity no matter what angle or direction they are viewed from. The intensity of a diffuse reflection will increase as the light source is brought closer to the subject.

The Inverse Square Law says "The intensity of the diffuse light reflected is inversely proportional to the square of the distance between the light source and the subject".

This implies that a light source at any given distance from a subject will lighten the subject with an intensity that is 4 times greater than the same light source moved to twice the distance from the subject.

An understanding of the behaviour of light is most definitely a prerequisite to understanding how to control the light when taking photographs. We see above that light can act on any subject that it strikes.

Its Intensity or brightness, colour temperature, and contrast are the three important properties that are, or should be, of most concern to the portrait photographer.

Portrait Photography Lighting - Summary

To recap, any subject will also act on light that strikes it whether through refraction, absorption, reflection, or indeed a combination of all three.

With portrait photography, the light is controlled in order to achieve optimum , balanced exposure of your composition to reveal and enhance the textures of your subject, its forms and colour saturation, and also to build a three dimensional perspective.

About the Author: Steve Barnes is a professional portrait photographer, freelance writer, and co-owner of Hayley Barnes Photography, in League City, Texas.

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