Lighting for Portrait Photography (Part 3) – Selective Control of Exposure

In Part 2 of this article, we explored the fundamentals of controlling overall exposure of a composition within the camera. The methods discussed are very effective for achieving the desired exposure of the overall image, the depth of field, and the perceived sharpness and graininess of a photograph. However, the photographer will generally want to emphasize a particular element within the composition, enhance a particular perspective, or suggest a particular mood. This may be accomplished in part, through carefully choosing or designing the elements of the composition. We have many classic rules to guide us in composition (e.g. the rule of thirds, negative space, color theory, etc.) Also, we may give special attention to posing our subject, or choosing a creative perspective or angle of exposure to emphasize a particular element, perspective, or mood. In my experience however, effective control over photographic lighting within a composition can be the difference between a masterful work and a mere snapshot. Light is the paintbrush in the art of photography. Controlling it is essential.

Over the years, many tools for effectively controlling lighting of a photographic composition have been devised. From scrims of all sorts, to flags, snoots, barn doors, and grid spots, to reflectors, umbrellas, and soft boxes, the tools in a photographers tool box may be neatly divided into three main classes. There are the tools for subtraction of light, the tools for addition of light, and the tools for modification of light.

Tools such as scrims, flags and even overhangs in the outdoors, are used to subtract light from the subject selectively to control emphasis, perspective, or mood. Filters and gels are a special case of subtractive tools. Some filters are used to subtract specific regions of the light spectrum, while gels are used to modify the color of light striking the subject also by subtracting specific regions of the light spectrum. Tools such as reflectors are used to add light selectively to the subject to control emphasis, perspective and mood within the composition.

Tools such as snoots, barn doors, grid spots, umbrellas, and soft boxes are used to modify a property of the light source used for photographic lighting. The properties commonly manipulated by the photographer are relative size of the source, specific placement of the light on the subject, fall off, and diffusion. In Part 1 of this article we learned that, “A light source’s relative contrast is generally determined by the size of the light source and its distance from the subject”. The light modifier tools of an indoor (studio) photographer function to control the effective size of the light source and thus control the contrast and fall off of the light striking their subject. For example, a large soft box may be used to modify a light source to increase it’s effective size, and thereby decrease the contrast of light striking the subject. On the other hand, a six inch parabolic reflector may be used to decrease the effective size of the source and increase the contrast of the light striking the subject. Generally the light modifier tools can be ranked in order of increasing size (decreasing contrast of light striking the subject): grid spots, 6 inch parabolic reflector, 16 inch parabolic reflector, 30 to 36 inch umbrella, small soft box (24″x36″), medium soft box (36″x48″), and so forth. The snoot and barn doors are typically used more to control specific placement of the light on the subject than as a means to control the level of contrast.

A basic understanding of the behavior of light, and how to effectively modify it using simple tools to control emphasis, perspective, and mood, is essential to your success as a photographer. Part 4 of this article will discuss the major classic styles of photographic lighting and we will see how these subtractive, additive, and modifying tools are effectively used by the photographer to create a masterful composition. Until then, good day and happy clicking.

Source by Steve Barnes

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