PHOTOGRAPHY BY ULTRAVIOLET AND INFRARED 



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Table I. — Sources of Infrared for Various Purposes 



General Infrared Photography: 



Sunlight 



Tungsten-filament lamps of high efficiency 



Studio- and projector-type lamps 



General-purpose lamps of 500 watts and higher 



Carbon arcs: flame, neutral-cored, and plain arcs and all types of studio and projection arcs 



Photoflash lamps 

 Cinematography : 



Sunlight 



All types of tungsten-filament lamps used for studio illumination 

 Medical Photography: 



All the sources grouped under General Infrared Photography 

 Photomicrography: 



Tungsten-filament lamps used in normal photomicrography, especially the ribbon-filament lamps 



Carbon arcs and enclosed metallic arcs, such as the Pointolite and Tungsarc lamps 



Mercury-capillary lamps 

 Documentary, Graphic Arts, Criminology, Scientific Record: 



All the sources grouped under General Infrared Photography 

 Photography in Total Darkness: 



The artificial light sources given under General Infrared Photography, especially the tungsten- 

 filament lamps and photoflash lamps 



which is itself colored. The filters most useful for general infrared work are red in 

 color, and if it is desired to confine the exposure to the invisible infrared when the plate 

 or film has some sensitivity in the deep visible red, the filters must be opaque. Filters 

 may be characterized by the wavelength below which they absorb radiation and above 

 which they transmit it. They must also be sharp cutting, i.e., the transition from 

 absorption to transmission must cover as short a range of wavelengths as possible. 

 The following table shows filters commercially available which are suitable for infrared 

 photography, as well as the wavelengths at which they cut. The filter selected for a 

 particular purpose will be chosen according to the minimum wavelength it is desired 



Table II. — Filters for Infrared Photography 



