What is Infrared Photography?
Infrared (IR) light — light that humans can't see, with wavelengths longer than those of visible light — was first discovered by Sir Frederick William Herschel in 1800.
Not to be confused with Far Infrared, or what we commonly see in X-Rays (thermal imaging), the lightwave lengths we use in photography are In the range from 700nm to 900nm, or Near Infrared.
The first Infrared photographs were taken in 1910 by Robert Williams Wood using photographic plates. Beginning in the 1930s film became available.
Today's digital camera internal filters, located in front of the sensor (digital "film"), are converted to block visible light to varying degrees (depending upon the range) and pass through infrared, basically capturing the heat of a subject.
So, for instance, in nature the leaves of deciduous trees or grass, which are throwing off heat, appear white; while pine trees or tree trunks, both cool in temperature, appear as one would expect, more true to life. It's a fascinating photographic genre that we'll explore more in the future.