Page 359 - Green - Maritime Archaeology: A Technical Handbook. 2nd ed

338 Maritime Archaeology: A Technical Handbook, Second Edition A. BLACK BACKGROUND
A black background, preferably velvet, can be used with all light objects. It is one of the best materials to use because it prevents shadows and reflec- tions. Great care should be taken not to crease the material and to keep it clear of dust and foreign matter. It is of no use for photographing very dark objects because of the lack of contrast, but it may be used with almost every- thing else.
B. WHITE BACKGROUND
This is usually white paper and it is one of the most difficult materials to use because of shadows. If the shadowing effects can be removed, however, the resultant photograph is extremely pleasing, appearing less heavy than the black background (see Figures 12.4 a and b). Various methods can be used to eliminate shadows. The use of a ring flash is a solution for small nonreflective objects although, as mentioned previously, there is always the worry of the unpredictability of the results. Because of the generally low power of the ring flash units, they are not of much use for larger objects. Problems can also occur when working with materials that have flat, reflec- tive surfaces, because the reflection of the flash is directed back into the camera lens and these effects may not be realized until the film is devel- oped. The ring flash is used for coins, small ceramic objects, and small metal objects. There is another way of removing shadowing occurring behind standing objects; place the object on a slightly raised stand with the back- ground some distance away. The background can then be separately illu- minated, and if the foreground illumination is reasonably high and to each side of the object, the shadows that exist will not be seen. Other solutions include a light tent, the use of diffuse daylight, and judicious use of development.
C. GLASS
Objects can be placed either on a glass plate some distance above a white illuminated surface or, alternatively, on a light box. Using this technique, the supplementary lighting burns out any shadows. This light box approach can be extended by creating an L-shaped white or opal Perspex surface which allows back illumination. When three-dimensional objects placed on the surface are illuminated from the front, any shadows cast will be burned out.