UV Fluorescence Photography of Works of Art : Replacing the Traditional UV Cut Filters with Interference Filters

• Main Author: Luís BRAVO PEREIRA
• Format: Article
• Language: English
• Published: Alexandru Ioan Cuza University of Iasi 2010-09-01
• Series: International Journal of Conservation Science
• Subjects: UV radiation; UV Fluorescence; interference filters
• Online Access: http://ijcs.uaic.ro/pub/IJCS-10-16-Bravo.pdf
• ISSN: 2067-533X; 2067-8223

For many years filters like the Kodak Wratten E series, or the equivalent Schneider B+W 415, were used as standard UV cut filters, necessary to obtain good quality on UV Fluorescence photography. The only problem with the use of these filters is that, when they receive the UV radiation that they should remove, they present themselves an internal fluorescence as side effect, that usually reduce contrast and quality on the final image. This article presents the results of our experiences on using some innovative filters, that appeared available on the market in recent years, projected to adsorb UV radiation even more efficiently than with the mentioned above pigment based standard filters: the interference filters for UV rejection (and, usually, for IR rejection too) manufactured using interference layers, that present better results than the pigment based filters. The only problem with interference filters type is that they are sensitive to the rays direction and, because of that, they are not adequate to wide-angle lenses. The internal fluorescence for three filters: the B+W 415 UV cut (equivalent to the Kodak Wratten 2E, pigment based), the B+W 486 UV IR cut (an interference type filter, used frequently on digital cameras to remove IR or UV) and the Baader UVIR rejection filter (two versions of this interference filter were used) had been tested and compared. The final quality of the UV fluorescence images seems to be of a superior quality when compared to the images obtained with classic filters.