Hello channel attendees. In this article I want to offer you a primer on infrared photography using the digital camera that you already own and to do so without having to make a permanent hardware modification.

What is Infrared Light?

The human eye cannot resolve all wavelengths of light, because what we call visible light is just a subset of the total electromagnetic spectrum. What we see is commonly in the range of 400 nanometers to 700 nanometers in wavelength. Nano is the prefix that identifies 10 to the minus 9th or nine positions to the right of the decimal.

Infrared light is simply light of a longer wavelength, between 700 nanometers and 1000 nanometers. The nature of this longer set of wavelengths passes through or is reflected by some subjects very differently than what we call visible light.

Gathering Infrared Data

Our common digital sensors today using a CMOS structure. CMOS stands for Complementary Metal Oxide Semiconductor and that’s more than most people need to worry about. These sensors are capable of seeing infrared wavelengths, but typically include an Infrared filter to block that light so as not to disrupt colour rendition in what humans see as visible light.

In order to allow the sensor to record data from the Infrared part of the electromagnetic spectrum, we can have our cameras permanently modified to remove the built in filter which is a destructive process or to use a filter in front of the sensor, usually mounted to the front of the lens to cut visible light and only pass Infrared light. It is less effective than removing the built in Infrared filter but works well enough, is non-destructive and is very inexpensive. This filter is called an Ir-Pass filter. When shopping for one, you purchase the filter diameter that attaches to the front of your lens and specify the filter type as R72. The effects will differ based on the existing light and the ISO that you use. Note that an R72 cuts visible light below 720 nanometers, which will demand longer exposures than those made without it.

There are firms that will do so called Infrared conversions, but all most of them do is put an Ir-Pass filter in front of the sensor permanently. It’s the same as using an Ir-Pass filter on the front of the lens except it costs more and is permanent. Despite plenty of hype, it doesn’t make logical sense.

Successful Subject Matter

Infrared photography works best with subjects that reflect a lot of light. Excellent examples include skies, foliage and water. Dull and non-reflective subjects do not work as well. Experimentation is key and the nature of the ambient light will make a huge difference in the success that you have.

Exposing for Infrared

Your camera light meter is not calibrated for infrared light, so while your in camera meter may get you sort of in the ball park, the presence of the Ir-Pass filter is going to impact the exposure accuracy significantly. Fortunately with a digital camera, you can see what you got in relatively short order, but understand that post-processing is going to be a critical step, so the LCD preview is going to be only of nominal value.

Focusing for Infrared

In the past, lenses had markers for focusing for Infrared. Your built in autofocus system is going to struggle with Infrared light, so the short and quick answer is use lots of depth of field to compensate for the focus being out a bit based on what the focus point(s) see. Use of a lens with a wider angle of view and a therefore greater depth of field at a given aperture and subject distance also helps.

White Balance

Your camera is designed to deliver white balance for visible light. There is no option for infrared light, so leave the camera in automatic white balance because you will HAVE to post-process anyway.

Post-Processing

Conversion to black and white is the most common treatment for infrared image processing, because it creates significant contrast and displays the effect of recording infrared light reflected from different subjects. Skies can go very dark, and foliage can go very bright.

Another option, fascinating but used less often is False Colour, where a visible colour is mapped to an infrared data level. This produces results that are interesting but strange wandering rapidly into creepy.

As in all things infrared, this is best served by experimentation. Presets are available but mostly they suck and blow simultaneously.

Wrapping Up

Infrared photography is fun and because the only real expense is a good R72 filter, pretty inexpensive. Gone are the days of requiring red filters and special film with special processing requirements. It’s a cool look and any creative photography should have this in their skill set.

Please become a member on Patreon to help support this channel. A big thanks to all the existing Patreon members! Send in comments or questions, I read and respond to all. If you shop with B&H Photo Video, please use the link on the main page as it pays me a small commission and does not cost you anything to do so. Thanks again and we will see each other again soon.