Digital photography

Ultraviolet photography

In reflected UV photography the subject is illuminated directly by UV emitting lamps (radiation sources). A UV transmitting, visible light blocking filter is placed on the lens, that allows ultraviolet to pass and absorbs all visible light. Examples of these filters are Kodak Wratten 18A, B+W 403, Hoya U-340, Baader U-Filter and Kenko U-360. These filters are made from special colored glass. Most types of glass will allow long wave UV to pass, but absorb all the other UV wavelengths, usually from about 350 nm and below. Only special developed lenses made of quartz (fused silica) or quartz and fluorite can be used. Using these lenses allow the camera to reach the range 180..200 nm. Lenses based purely on quartz show a distinct focus shift between visible and UV light, whereas the later developed fluorite/quartz lenses are fully color corrected without focus shift. Examples of the latter type are the Nikon UV Nikkor 105 mm, the Hasselblad (Zeiss) UV Sonnar 105 mm and the Asahi Pentax Ultra Achromatic Takumar 85 mm.