Leaves of Grass, The Sensual Land
It looks like another world, yet it’s not. By opening a window into a spectrum we can’t see with the naked eye, infrared photography shows us our world in an extraordinary light.
The human eye is sensitive to a range of light varying between 400-700 nm (nanometers). Infrared exposure typically filters the majority of that range of light out and favors frequencies between 780-900 nm, frequencies the human eye can’t see. Though we can’t see it, we are surrounded by and often use infrared light on a daily basis. Today, many household and office devices employ infrared transmissions – remote controls, security alarms, printers, and laptop computers.
To be sure, rendering the invisible visible is an unusual proposition. The best we can do is to simulate it, typically by representing the invisible with a color or tone that we are capable of seeing. This causes some overlap between subjects that visibly contain the substitute color and subjects that reflect more infrared light. Both color and black-and-white film render infrared light in a variety of ways. The effects of black-and-white infrared are largely limited to value (greater concentrations of infrared light are rendered lighter) while color infrared exposure adds shifts in hue (more infrared light, redder and sometimes lighter).
Infrared effects are dependent on the scattering and absorption characteristics of materials that reflect light. The photosynthetic pigment chlorophyll, found in plants, reflects infrared light, causing these materials to appear very bright. Skin reflects infrared wavelengths while blood absorbs them, so skin looks transparent, veins sometimes become more apparent, and eyes become very dark. Sunglasses that appear opaque when reflecting visible light may suddenly seem transparent. Water and atmosphere scatter blue light and absorb infrared wavelengths causing these materials to appear very dark. As a result, atmospheric conditions can modify results, significantly reducing the effect.
The effects are often unpredictable and almost always surprising. Perhaps, that is why this effect is so compelling.