Visitor Assessment Studies
Current lighting practices nearly always display light-sensitive artifacts under low levels of incandescent lighting. Both of these factors—low light levels and incandescent lighting—provide challenges to viewing. The spectra of incandescent lamps tend to be weaker in the blue region than sources with higher color temperatures. This influences color rendering when compared to whiter light sources like daylight, and thus subtly alters a viewer's color perception. Low light levels make seeing dark surfaces, low contrast compositions, and those with high detail more difficult. These conditions are of particular concern for older museum visitors. These combined factors alter the aesthetics of artwork, and the trade-offs (in terms of increased preservation) are overarching—dictating to the museum patron what he or she shall see.
New (filtered and solid state) light sources will have their own challenges, and it will be important to determine how closely they match older light sources in color rendering and visitor satisfaction. If there is little difference, the conservation benefits will clearly exceed those of the older sources, and add no new limitations and liabilities to their usage. This would be a good outcome. It is also possible that a new lighting source might appear to be brighter and will have conservation benefits. This would be an ideal outcome. Most likely this will not happen easily, necessitating adjustments in the earlier filter profile and the manufacturing of a new design followed by reevaluation. Ultimately, this would continue until no further improvements can be made and the outcome is deemed a valued improvement. To some degree these comparisons can be anticipated through mathematical modeling, but carefully considered opinions from human observers should be the final arbiters.
To this end, this area of research has created a sample viewing population of museum docents, conservators, and curators. This population represents a wide age range and is skewed in favor of highly critical viewers and museum decision-makers.
An experimental lighting facility (ELF) was built at the Getty Center to control display variables and to realistically simulate museum galleries. Track and fiber-optic lighting were compared and fundamental questions on color rendering preferences tested. It was designed to accommodate the needs of the different component teams, either working independently, or in coordinated research.
As new topics arise, the ELF is flexible enough to carry out advanced research. One possible topic for advanced research is development of a redefined or specialized version of the color rendering index (CRI) designed specifically for use in museum lighting. The current protocol for determining CRI of a light source doesn't include the types of colorants likely to be found in museum collections, it is skewed to give incandescent light sources a preferentially higher value than a non-incandescent source of the same low color temperature, and it doesn't accommodate secondary reflections from the total gallery environment.
Last updated: November 2012