Positioning Lighting

Artifacts and small objects can be photographed by daylight, although direct sunlight can produce both over-lit and deeply shadowed areas that may obscure important details. Direct sunlight may be diffused by placing a piece of neutral muslin stretched on a frame between the object and the sun; a reflector can help cast light into the shadows.

Many cameras have built-in flash guns, while others have a fitting for a flash known as a hot shoe (see figure 17). On many 35mm single lens reflex cameras (SLRs), the shoe is usually above the lens, with the result that the light emitted by the flash reflects straight back into the lens, resulting in patches of glare (hotspots) appearing on photographs of objects with shiny surfaces (e.g., varnished paintings, glass surfaces and objects, or porcelain). Attaching the flash to a separate flash bracket to one side of the camera can reduce the amount of reflection (see figure 18).

The general rule when many types of objects are photographed is that the main light on an object should come from above, preferably from the top left. We are all accustomed to seeing the world lit from the sky, and top-lit objects are therefore the easiest to recognize. With some two-dimensional or shallow objects, this one key light is sufficient. If the object is three-dimensional, either a reflector or a fill-in light will be needed on the opposite side of the object. It may be necessary to use another reflector or even a third, smaller, light to show a particular detail of the object. It is useful to devise a few reflectors of different sizes for such purposes. The cheapest and most effective are pieces of card stock covered with crumpled and re-flattened aluminum foil.

After shape, the second main consideration is texture, the visibility of which is dependent on the strength and direction of the lighting. Acutely angled lighting will emphasize texture, and frontal lighting will flatten it (see figure 22). It is as deceptive to over-emphasize texture as it is to suppress it, although exaggeration of texture might be used in some instances to increase the visibility of a distinguishing feature. The angle of lighting must be related to the fineness or coarseness of the surface. For example, if light is just skimmed across the surface of a flat piece of limestone, it may show the grain of the stone very clearly, but light at a similar angle across a deeply incised bronze plaque, or a heavily wheel-marked pot, may give the impression that the plaque is pierced with slits, or the pot ridged, especially if the light is not balanced with a supplementary source.

The direction, type, and intensity of light will depend on the size and type of object being photographed. Most small objects can be photographed adequately using oblique lighting—that is, with the main light falling across the relief of the object, so that the surface is in a rather darker tone. Cross-lighting of this sort may also produce quite hard shadows, and a reflector may be needed to bounce light back into them. A reflector of crushed and re-flattened aluminum foil, or a low "wall" of foil curved around the object, can be quite satisfactory (see figure 23). Highly reflective objects such as beads and individual gem stones often respond best to completely diffused light, which can be achieved by surrounding the object with a translucent wall or cone of paper or plastic, then shining the lights onto this surface from the exterior (see figure 24).

Light, polished metal, and dark rough metal surfaces require quite different types of lighting from ceramics. Light-colored metal, especially silver, is difficult to light without obtrusive reflections. The best lighting of all is usually diffuse daylight (not direct sunlight), although it may be necessary to position a reflector below and in front of the object to give some light in the shadowed areas. If it is not possible to use daylight, then the lighting should be made as diffuse as possible. The lights can be shined against large reflectors (sheets of paper or foil) instead of on the object, or against walls or ceilings to reflect diffuse light onto the object. When using color film, care must be taken not to reflect light from colored surfaces. Dark, rough metal presents a different problem. If the angle of light reaching the object is too low, surface irregularities might show as hard points of light, and throw shadows on the rest of the body.

Glass objects with simple shapes against illuminated backgrounds often need no other lighting. Cut, etched, or engraved glass, however, will usually need some frontal lighting to show details. This is best achieved either with very soft, overall lighting, or with a single, small light source positioned so that its reflection falls on an unimportant area. As with polished metal, diffused daylight is often the best illumination for glass objects. In photographing furniture, statuary, and sculpture, soft overall lighting is preferable. If the piece is not on or against a white background, it may be necessary to place a reflector below and in front of it to illuminate the shadows slightly. Dramatic cross- or top-lighting should be avoided in record photographs. A single, strong light source can result in confusing shadows beneath or behind the piece. A useful technique when photographing sculpture is to take the picture in a darkened room, using a long exposure and with the illumination provided by a moving light (figure 25).

Flat objects such as paintings, drawings, and prints require lighting that is as even as possible. This can be achieved by using daylight, although it may be necessary to place a reflector below the original. Two tungsten lights on stands, set at about 45 degrees to the surface, can evenly cover an area. For large objects, four lights may be needed, one at 45 degrees to each corner, both vertically and horizontally, at a distance of 1 or 2 meters (see figure 26). The evenness of the lighting can be checked by taking a series of light-readings on a gray card held in the middle and at the four corners of the object.

Stained glass, wall paintings, and mosaics normally must be recorded in place. When recording mosaics, do not wet the tesserae before photographing the panel or pavement. This can be damaging to the surface and/or the bedding materials, and can also cause unwanted reflections. Lighting can be slightly directional to show the roughness or smoothness of the surface; if the mosaic is of the type with the tessarae slightly tilted in order to catch the light from one direction, the main lighting should come from this direction. A small, fill-in, flash unit can sometimes be used to reinforce the directional light. Mosaic or tiled pavements are often difficult to photograph because of their size and position. Unless the photographer has access to a gantry, or to the interior of the roof of the building, it is difficult to obtain a square-on view. All that can be done is to achieve as high a viewpoint as possible and to make sure that the image is quite sharp front-to-back.

When lighting carved, flat-faced objects, such as tablets and detached inscriptions, the main light should always come from the top or the top left — never from beneath — and the angle of the light must be adapted to the material. Either flash or tungsten lighting can be used, but the light source should be sufficiently far away that there is no appreciable fall-off of light across the surface. With tablets or deeply cut inscriptions, a reflector should be positioned opposite the main light: otherwise details may be lost in shadow. In the case of small, flat-faced objects with incised or raised detail, small differences to the direction of the lighting can have dramatically different effects (see figure 29).