Ultraviolet Fluorescence Photography
Photography based on (visible) fluorescence induced by UV radiation has better results in archaeological photography. The same ultraviolet light sources as in reflected UV photography, except that a glass filter is used to absorb all the visible light and allow only the desired ultraviolet to pass. These filters are sometimes incorporated in the source tube itself, but most of the time are separate elements. These filter glasses usually allow a small amount of violet visible light. This should not be confused with UV light, which is invisible to the human eye. The same kind of filters are made for flash tubes also, by BALCAR and other lighting companies.
This filter is called an "exciter" filter and it allows only the radiation needed to excite fluorescence. A second filter must be placed in front of the camera lens, to exclude residual ultraviolet and allow the resulting fluorescence excited in the sample by the UV source. This filter is called the "barrier" filter. Kodak Wratten 2A - 2B is effective, as is the Baader UV/IR Cut filter. Using a 2E filter gives better results in some situations. The same filters are also made by other companies with the same codes.
The shooting must take place in a darkened room, with a black background. The photographer should also wear dark-colored clothes for better results. (Many light-colored fabrics also fluoresce under UV.)
Suitable digital cameras for reflected UV photography have been reported to be the (unmodified) Nikon D70, D40 and Fuji Film S5 cameras, but others might be suitable after having their internal filter removed. If using a modern digital camera (DSLR), it would be advisable to additionally use an IR blocking, yet UV transmissive filter to avoid IR leakage. Schott BG-38 and BG-40 are suitable for this purpose.
The Fujifilm FinePix IS PRO digital SLR camera is purpose-designed for ultraviolet (and infrared) photography, with a frequency response rated from 1000-380 nm, although it also responds to somewhat longer and shorter wavelengths. Silicon (from which the sensor is made) can respond to wavelengths between 1100-190 nm.
Read more about this topic: Ultraviolet Photography, Equipment and Techniques
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