3 Studio Photography Techniques
Summary
This chapter discusses proper use of studio conditions to create optimum medical images. Light quality, the use of light modifiers, proper arrangement and use of lights, and use of photographic backgrounds are explained in detail with attention to producing repeatable, reliable photographic results.
Keywords
background, grid, hair light, light quality, light modifier, soft light, softbox, strobe, umbrella
Introduction
Studio photography allows for tight control of every aspect of the environment, light, and camera placement to create reproducible, consistent results. The lighting process is by far the most important factor in studio photography. Through the careful use of multiple flashes and light modifiers, the perfect light is created to accurately and consistently depict the patient’s condition.
3.1
Light Quality and Light Modifiers
Photographers describe the appearance of light by various parameters, but most importantly as hard versus soft (Fig. 3.1). Hard light produces sharp, highly defined contrasting shadows. Examples of hard light are direct sunlight or a bare flash bulb. Soft light is characterized by gradual transitions to shadows, and is less directional. Examples of soft light are diffused window light or a flash in a softbox. Two factors influence the hardness of light: the size of the light source and the distance from it to the subject. Larger lights closer to the subject produce softer light. For medical purposes, soft light best depicts skin quality and texture.
The size of light source used in the studio is fixed, and it can only be placed so close to the subject without interfering with their comfort. Thus, the light source must be diffused to have a larger effective area, by use of tools such as softboxes and umbrellas (Fig. 3.2). Softboxes are large, cloth boxes faced with white diffusion fabric, and result in very soft but somewhat directional light. Umbrellas can be either reflective or shoot-through; a reflective umbrella has the flash aimed away from the subject and the umbrella reflects the light back toward the subject. A shoot-through umbrella is made with a similar diffusion fabric as the front face of the softbox, and is placed between a flash aimed at the subject to diffuse the light. Any of these three can be used, but shoot-through umbrellas and softboxes generally allow better soft fill. In many cases, a subtle shadow fill of select areas using a reflector is useful. Only white or silver should be used so as not to induce a color cast. An example of reflector use is on the patient’s lap, to fill in the shadow created under the chin and nose. In some situations, restriction of light to only illuminate select areas of the frame is needed. This is accomplished with light modifiers such as grids, flags, or gobos (short for “go-betweens”). In medical photography, the only common use for this is with “hair lights” discussed later.
3.2
Lighting Design and Setup
In medical photography, the aim is to create extremely smooth, even lighting that illuminates as much of the subject as possible, with no areas of deep shadow or overexposure. This can be accomplished by many methods, two of which are described below. Two lights are necessary at minimum, but additional lights can be used for added benefit.
The easiest light setup is the use of two strobes with umbrellas or large soft boxes, positioned a few feet above head level and a few feet from the camera to the right and left. The strobes should be metered to provide perfectly balanced illumination to both sides of the face (1:1 lighting ratio). This will produce soft, even illumination of the subject and background, and the shadows cast by the lights will largely fall off-camera. The addition of a reflector positioned on the patient’s lap can be beneficial for fill light. While it is not required, the addition of gridded hair lights positioned behind the patient and directed at the back of the head can help increase the apparent separation of the patient and the background (Fig. 3.3). If this is done, care should be taken to avoid excess spillage or halo that would obscure the contour of the face.
