A Site for Photographers by Photographers

Ultraviolet Photography

Ultraviolet radiation has a shorter wavelength (higher frequency) and higher energy than light from the visual spectrum. The ultraviolet spectral range starting below 400 nanometers can be photographed with conventional films and cameras. The extended regions of ultraviolet will be filtered by glass lenses and expensive quartz lenses will be required.

Ultraviolet photography can be done under sunlight, electronic strobe, UV grow lamps designed for indoor gardening and various UV lamps designed for scientific applications. A large lighting supply company can provide UV florescent bulbs in both the UV-A (longer wavelength blacklight) and UV-B ranges (shorter wavelength and visually harmful). These can be used in ordinary florescent fixtures. Light boxes, soft light fixtures and floodlamps can be easily constructed using these materials. Commercial UV lamps can be purchased from the following sources:

Edmund Scientific Co.
101 East Glouchester Pike
Barrington, NJ 08007-1380, USA

Hanovia Lamp Division
Emglehardt Hanovia, Inc.
100 Chestnut Street
Newark, NJ 07105, USA

Harkshaw Scientific
1945 East 97th Street
Cleveland, Ohio 44106, USA

Matheson Scientific
1850 Greenleaf Avenue
Elk Grove Village, IL 60007, USA

Ultra-Violet Products, Inc.
5114 Walnut Grove Avenue
San Gabriel, CA 91778, USA

There are two types of ultraviolet photography - reflective and fluorescence. The requirements and techniques for these are entirely different, so they are dealt with separately.

Ultraviolet Reflective Photography

Reflective ultraviolet photography is just like visual photography except using ultraviolet illumination. Ultraviolet light is reflected or absorbed by the subject. A Wratten #18A filter can be used to eliminate visual spectrum. This filter has a filter factor of about 80 (plus 6.5 f-stops). The following company specializes in filters for scientific uses:

Rolyn Optics Company
706 Arrow Grand Circle
Covina, CA 91722-2199, USA
FAX: 818-915-1379

Rolyn produces many types of 50.8mm (2 inch) square unmounted filters that are very useful for spectral selectivity. Rolyn's catalog provides a spectral sensitivity plot for every filter they make. Prices are not unreasonable for scientific quality filters - some of the simple color filters are in the $30 to $50 range. Larger sizes and esoteric types can get expensive. You will have to devise a filter holder. The over-the-enlarging-lens variable contrast filter holders for VC enlarging paper works.

Ultraviolet Fluorescence Photography

Fluorescence ultraviolet photography involves photographing the glow or fluorescence produced by some minerals or other substances when excited by ultraviolet illumination. In the case of fluorescence photography it is usually desirable to minimize reflectance imaging so as to emphasize the fluorescence. The fluorescence is typically in the range of the visual spectrum so that a UV cutting filter such as the Wratten #2E is useful for blue fluorescence. The much stronger UV cutting Wratten #6 or #8 (yellow), or a light balancing #81EF can be used with green, yellow and red fluorescence. These filters are typically placed over the lens.

Eye damage is possible with UV illumination in the UV-B or shorter wavelength region. Never look directly at a UV-B light source. Even reflected illumination from a UV-B light source can be harmful. Always exercise great caution when working with UV-B illumination. The damage it can do to your eyes is irreversible. Looking through a camera lens, with a Wratten #2E filter attached, for short periods of time to compose and focus the photo is usually safe.

Exposures always need to be determined by trial and error since fluorescence is unpredictable. A 100 daylight ISO film with 100 watt UV lamp 6 inches (15cm) from a subject will typically require exposure times in the 1 to 16 minute range at a lens opening of f-5.6. Aluminum foil makes an effective UV reflector for illuminating multiple sides of a subject UV excitation illumination. Cardboard and tape can be used to construct a parabolic UV reflector to concentrate higher UV illumination levels on a small subject. Front surface mirrors work as well as aluminum foil but cost more.

Infrared Exposure
Spectral Selectivity
Ultraviolet Photographic Materials

C1997 by Ed Scott - <dotted.dog@worldnet.att.net>
Return to photo.net