Recording what the eye does not see
Infrared photography is the ability of the film or sensor to record what the eye cannot see (permitting, for instance, photography in the dark); in the fact that many materials reflect and transmit infrared radiation in a different manner than visible radiation (light); in the ability of infrared radiation to penetrate certain kinds of haze in the air so that photographs can be taken of distant objects and in the ability to photograph hot objects by the long-wavelength radiation that they emit. These properties permit infrared photography to be used as an important adjunct to photography by normal light.
A 1973 infrared Volkswagen Beetle Courtesy of Mehmet Ergun
The portion of the gamut used is often called near-infrared to tell it apart from far-infrared, being the province of thermal imaging. Wavelengths employed for photography ranges from approximately 700 nm thru around 900 nm. A "infrared filter" is typically used to let IR (infrared light) enter the camera, however blocks all or the majority of the perceptible light band (Consequently the filter appears deep red or black).
By combining these filters with infrared-sensitive sensors or film, very fascinating "in-camera effects" are able to be achieved; black & white images (false-color ) containing a dreamily like or every so often a lurid look called a "Wood Effect," a consequence caused mainly foliage (like grass and tree leaves) tenaciously reflecting in a similar manner perceptible light is mirrored from snow. Chlorophyll fluorescence plays a small role in this, however it's extremely small and isn't the genuine cause for the brilliance observed in infrared photography. This consequence was named after Robert W. Wood the pioneer of infrared photography and not named after the wood material, which doesn't glow underneath infrared.
The other characteristics of infrared photographs feature extremely darkened skies plus atmospheric haze penetration, created by concentrated Mie scattering and Rayleigh scattering, respectively, as compared to observable light. The darkened skies, in turn, are a consequence of less infrared light within shadows and darkened reflections of those resulting skies coming from water, while the clouds will strongly stand out. The skin is also penetrated few millimeters by these wavelengths and gives off a milky appearance to portraits, although the subject's eyes often seem black.