Ultraviolet Photography

Some materials will absorb ultraviolet, while others will reflect these radiations. Some have partial reflection. These effects can be recorded photographically suing ultraviolet radiation. Black-and-white films are sensitive to most wavelengths of ultraviolet. By using a filter that absorbs all visible light but passes ultraviolet, it is possible to make a photographic exposure with just ultraviolet.

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Uses in Law Enforcement

  1. Try ultraviolet photography after visible light techniques and infrared light techniques fail (questioned documents, etc.).

  2. Fingerprints on multicolored surfaces (dust with fluorescent powder or ninhydrin).

  3. Body secretions such as urine, semen and perspiration often glow when illuminated by ultraviolet light.

  4. Money and other valuables can be dusted or marked to identify thiefs.

Equipment, Films and Filters

  1. Camera and lens with a Kodak Wratten filter #18A.

  2. Other light sources include mercury vapor lamps and wire-filled flash lamps.

Focusing and Exposure

  1. Focus for visible light and then shoot for maximum depth of field to get the correct focus.

  2. Accurate focus and exposure for ultraviolet photography requires test exposure.

  3. The ISO of film will be much different for ultraviolet photography. A film with a speed of ISO 400 for visible light may have an effective speed of ISO 10 for ultraviolet photography. Bracket your exposures.

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Photographic Necessities for Reflected Ultraviolet Radiation

  1. Illuminate the subject by means of a radiation source that emits ultraviolet.

  2. Exclude all visible light from the camera by placing over the lens a filter that transmits only ultraviolet.

  3. Record the image in the camera on the film.