Introduction to Object ID
  Project Team
  Part 1
  Part 2
part 2: positioning lighting

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).

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Figure 17:  Cameras with, left, a flash unit fitted on a hot shoe attachment and, right, an integral pop-up flash unit.

Figure 18:  A hammerhead flash unit mounted to the side of a camera using a flash bracket.

If the flash gun has an adjustable head, the brightness of the light can be softened by bouncing the light off an angled piece of white card positioned above the flash (see figure 20). In addition to general-purpose flash guns, a number of more specialized types are available, including the ring flash (a circular flash unit that fits around the outside of the front of the lens), most often used in close-up photography of small objects (e.g., coins) to produce localized, shadow-free lighting (see figure 21).

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Figure 19:  A flash unit on abracket with a reflector.

Figure 20:  A ring flash unit mounted on the lens of a 35mm SLR camera.

For black-and-white photography, two domestic desk lamps with ordinary incandescent bulbs can be used with, if possible, a third lamp to light the background (see figure 21). However, with color film, these lights give a decidedly yellow cast to the result; even using a color-correcting filter cannot be recommended, as the color of the light of such bulbs can vary widely.

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Figure 21:  An object lit by two desk lamps with incandescent bulbs can be supplemented by, if possible, a third lamp to light the background.

Another type of electric lighting that is commonly used in both black-and-white and color photography is tungsten and tungsten-halogen. Low-wattage tungsten bulbs (up to 200W) are adequate for use with black-and-white film, but are not suitable for use with color film. Higher-wattage tungsten bulbs (e.g., 500W) are designed for use with tungsten balanced films. However, they also produce a considerable amount of heat, which means that for many organic materials, such as wood, paper, fabrics, etc., the lights must not be left to shine on the objects for long periods of time.

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.

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Figure 22:  Acutely angled lighting emphasizes texture, right, while front lighting, left, flattens it.

The third consideration taken together with texture is tone and color. With black-and-white photography, tone (the ranges of grays between black and white) is all-important. The only reliable way of ensuring that the range of tones of the print will match those of the original object is to include a gray scale (see Scales and Labels) in the photograph, making sure that it is lit in the same way as the object. For color photography, a color reference scale is also needed.

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).

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Figure 23:  A reflective low wall of crushed and reflattened aluminium foil used to bounce light into shadows produced by the light source.

Figure 24: Highly reflective objects require diffused light. This can be achieved by surrounding the object with a translucent wall or cone of paper or plastic and then shining the lights onto this surface from the exterior.

When lighting ceramics, the main light should come from the top left, with a fill-in light farther away on the lower right. However, there is a special problem with glazed and burnished wares and porcelain: Lights reflected from the surface may mask the texture, tones, or details of the pot, while if the lighting is so soft and overall that there are no reflections, the vessel may not appear to be glazed or burnished at all. Often the best solution is to use one main light plus a reflector and, looking from the camera position, to move the light about until its reflection falls on an undecorated or unimportant part of the pot’s surface.

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).

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Figure 25: 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.

Some materials are particularly difficult to light. White marble or limestone may appear to lose its texture if the lighting is too frontal, while dark materials like granite or cast bronze may need a great deal of indirect light to reveal their textures. Dark, shiny stone like polished basalt is especially difficult to light, and strong illumination is needed to show the texture of the surface. Overall, very diffused light is usually the best answer and daylight is the best source, if this can be arranged.

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.

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Figure 26:  For large objects such as a drawing or a painting, four lights may be needed, one at 45° to each corner, both vertically and horizontally, at a distance of 1 or 2 meters.

Lighting canvas and panel paintings for photography is easiest when they are removed from the wall, but if this is impractical, there are options. The first challenge is to achieve even lighting without excessive reflection. With oil paintings with thick brush-strokes (impasto), it is often necessary to move the lights from their normal 45-degree position to a shallower or a steeper angle. A polarizing filter may also be useful for cutting glare from the shiny paint layers. Because dark oil paintings, and to a lesser extent, works of tempera can appear muddy and indistinct, it often helps to flood such paintings with light, and to over-expose the photograph. They often respond well to infrared photography (see figure 28). They may also be even more dark and obscured than oil paintings, with a surface coating of lamp-black. Normally such a procedure would produce a poor result, as the lightest areas would lose detail. But with an uncleaned painting, the lightest tones would themselves be comparatively dark, and there should be little distortion of the tonal range. For record photography, it is advisable to include the frame in the photograph.

Figure 28:  Dark oil paintings, difficult to photograph with black-and-white film, top, often respond well to infrared film, bottom.

Icons are very similar to oil paintings to photograph, except that they may include areas of precious metals that may cause problematic reflection. If they can be moved, the back should also be recorded, together with any inscriptions. If a number are mounted together, as on an iconostasis, each should be recorded individually and the whole group photographed in order to locate each in its position relative to the whole.

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).

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Figure 29: Small differences in the direction of the lighting can have dramatically different effects in the case of small, flat-faced objects with incised or raised detail. The object pictured here was photographed with a single light, top left; multiple lights, top right; flat, reflected light, bottom left; and a ring flash, bottom right.

For fabric and basketry, even, overall lighting is all that is normally needed. This can be achieved by using daylight, or by using four tungsten lamps arranged well away from the object. For detailed work, quite strong cross-lighting may be necessary, and it can be productive to determine the best arrangement by moving the light around the object while watching the effect. Often, such things as secondary textures and folds in the material will be shown up in this way.

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