OUR EXPERT Mike Bedford has dabbled with infrared photography for some time. As he’s discovered, though, using a Raspberry Pi can open up some exciting new possibilities without breaking the bank.
QUICK TIP
Reference to wavelengths might seem positively archaic, with radio waves having been referred to by their frequencies instead of wavelengths for several decades. Wavelengths are still commonly used when referring to light and infrared, though.
QUICK TIP
Reference to wavelengths might seem positively archaic, with radio waves having been referred to by their frequencies instead of wavelengths for several decades. Wavelengths are still commonly used when referring to light and infrared, though.
Infrared is commonly thought of as heat, but I that’s only true of far infrared. Closer to visible light – in fact, immediately adjacent to the red end of the visible spectrum – is so-called near infrared. And while far infrared can only be photographed using special cameras, near infrared can be photographed with ordinary cameras, more or less. So, near infrared photography, which we will refer to as simply infrared photography, is much more accessible.
You could use most phones or ordinary cameras for infrared photography (see LXF248) but here we’re using Raspberry Pi NoIR cameras. For reasons we’ll see, these offer several benefits, including the ability to create attractive false colour infrared images. After providing a quick overview of infrared itself and infrared photography, we’ll move on to a couple of practical themes. First we’ll see how to take infrared photos, and then we’ll look at the crucial subject of post-processing. So, if you find the prospect of photographing the invisible intriguing, and are prepared to spend a very modest amount of money, you have come to the right place.
Infrared – the basics
It’s good to know something about infrared, and not just out of a desire for knowledge. Infrared, as well as visible light, are both a type of electromagnetic radiation and they are differentiated by their wavelengths. The visible spectrum ranges from purple light, which has a wavelength from around 400nm, through indigo, blue, green, yellow and orange, to red light, which has a wavelength up to around 750nm. Immediately above this we find infrared, which is considered to cover a huge range of wavelengths, from 750nm to 1mm. Of this, near infrared covers wavelengths of 750nm to 1,400nm.
Don’t underestimate the appeal of black and white photography, and infrared makes it even more spectacular.