The human eye sees light waves in the range of 400 nanometers (a measurement of the length of a light wave equal to one billionth of a meter) to 700 nanometers (nm).
We see light waves of 400nm as the color violet and those of 700nm as the color red. In between, we perceive the range of light wavelengths as a smoothly varying rainbow of colors, known as the visual spectrum. Light waves shorter than 400nm and those longer than 700nm are invisible to the naked eye.
Cameras, however, can “see” light waves outside of our visual spectrum.
Just above our visual spectrum, in the range of 700nm to 1400nm, is the near-infrared (IR) spectrum. Cameras can be adapted to capture light in this spectrum, offering the photographer some interesting creative options.
For IR work, I use a Nikon D200 camera converted to record light at 720nm, which is known as a standard IR conversion.
While photographers normally avoid shooting in bright sunlight, preferring to seek out the “golden hour” of early morning or evening, IR photography works best in bright sunlight. This is because, when sunlight strikes green leaves and grass, the chlorophyll in the vegetation reflects huge amounts of infrared light, which is captured by the camera’s specially-adapted sensor and rendered as a ghostly white.
The resultant image can then be processed either as a color image (within the limited range of colors available in that part of the light spectrum) or converted to black and white (B&W).
To my eye, an IR image converted to B&W, such as the blog image, produces a look which is different from normal B&W photography (shot in visible light). So, it offers the photographer a unique form of visual expression.
Not content with shooting IR, I have also been experimenting with High Dynamic Range (HDR) photography in IR light. HDR permits the photographer to capture a greater range of light – from bright highlights to dark shadows – than the camera’s sensor can capture in a single exposure. For this shot, the camera could not capture both the bright reflections glinting off the chrome grille of the truck and the shadows cast on the grass.
This image was made by shooting a series of three exposures shot at different exposure values (f25 at 1/20th sec, 1/13th sec, and 1/5th sec), then merging them into a single, correctly-exposed image in post-processing, using the Nik HDR Efex Pro 2 plug-in for Photoshop. In processing the image, I increased the tonal contrast and structure to make the sky really pop.
Of course, it helps if you have dramatic clouds in the sky to start with. This image was shot in early June, 2013 in the Palouse area of Washington State, which has some of the most dramatic skies to be found anywhere.