Infrared Photography

Text and pictures © 1993-2024 Guillaume Dargaud
Last updated on 2021/11/05

"Infrared photography calms me. I love it."    — Irene Müller.

Beyond visible light

Left: Jenny taking the pause on a patch of wild strawberries. Light coming from the back with tree branch overhead.

Infrared photography is something I'd meant to do for the longest time. In the time of film photography it was highly unwieldy, films having to be kept at low temperature and processed immediately after use. Digital photography now offers easier possibilities, but at a price: where both B&W and color IR films were available, you now have to content with what the CCD can give you. Or more exactly what the filter can leave in for you. The sensor of the camera, when taken by itself, is sensitive to visible colors (red, green and blue), but also to infrared and ultraviolet. In normal circumstances this is considered a hindrance, so a specially crafted filter is placed atop the sensor to let only visible light through.

Right: Freshly harvested haystacks in the field. This is not quite impressionist's Monet, but the eery light is there.

The most obvious solution would be to remove that filter. Unfortunately on most cameras that is not possible as the filter is integrated to the sensor, it's difficult to take apart, and anyway I don't know which cameras have removable filters, with the notable exception of the Canon G1.

Left: Infrared haystacks and rest (digesting ?) model.

Another solution is to purchase a camera that can directly do IR and UV photography. There are a few such (expensive) cameras, for instance the Fuji IS Pro, a variant of the popular Fuji S5 SLR. The drawback is the price, the fact that you need a totally impossible to find fluoride lens if you want to do UV photography (UV-Nikkor 105mm or EL-Nikkor 63mm), and the final fact that those cameras are associated more with forensics, dead bodies and unpleasant things like cops and coroners than with artistic photography !

Right: The willow turns into a frozen waterwall thanks to the magic of light filtering.

The easiest solution is to use the weakness of the filter against itself. In theory it doesn't let any IR light go through, in practice, the cutoff frequency isn't so sharp: some will always go through, provided you are ready to wait long enough. So what do you need in this case ? A low-pass IR filter to screw on your lens, a tripod and some trial and error. The quality is not up to what you can get with the previous two solutions but you can still get some interesting images.

Left: Same willow, same haystack and same model.

For those images, I used my aging Ricoh GRd, with the optional GH-1 hood as a filter holder and a B+W 37mm Infrared Filter 093. A quick evaluation gave me an average exposure time of about 4s at f3.5 in full sun ! It takes a patient model for those shots, but it's okay, as we were still digesting 2 pound lobsters.

Right: The main problem with doing 4s long exposure is that the noise level increases sharply on the image and for instance the sky is no longer smooth.

With most lenses, the focal plane for infrared is off with respect to visible light, meaning the focus won't be correct, but with digital compact cameras the depth of focus is so huge that it'll hardly matter. I just used [snap] mode, but maybe [infinity] would have been more appropriate.

Left: The tree is glowing but Chernobyl has hardly anything to do with it.

So I proceed like in the old days: put the camera on a tripod in full sunlight, frame by dead reckoning, set the self-timer to 2s and trigger, tell my model to catch a deep breath and freeze, count down to 4 and bingo, I get am eery-looking shot. So what's the result ? It's like the use of a red filter with B&W photography, only more so. The skin takes on a kind of glow, and you can even see the veins through. In some cases you can see through light clothing for all you perverts out there. Green leaves turn out white. Snow turns out black (it's cold !). Skies are bright blotchy clouds set on ink-black skies.

Right: Morgan le Fay invoking the waters of the mud puddle in search of some Arthurian twig.

Left: Grass floating on the water has time to leave a trail on the long exposure image.

Right: Faery house under a willow.

Left: An average concrete staircase seen afresh with infrared vision.

Right: Tree-porch.

Left: The old oak tree appears snow-covered: the green of chlorophyll reflects infrared.

Left: My own harvest fairy walking through the fields.

Processing

When you take the image with the filter on your digital camera, the result may not be what you expect if you have seen a few IR images on the web. First of all, you might as well set your camera to Black and White mode right off the bat. If you leave it in color, the result will look like the image on the right. And then again it may look completely different, depending on what kind of wavelengths manage to pass through the combination of IR filter and visible filter. Contrast is very low. Intensities in the 3 color channels are very different, explaining the strong cast.

So in term of processing, I take a RAW and then feed it into SilkyPix. There I push the contrast to the max to 2.5 (the histogram is useful), lower the center of the contrast, push the black point as far as 30%. I also remove sharpness which would only increase the grain. Then I either convert it to B&W using the Monochrome2 (which puts more weight on the red channel) or do heavy color temperature tweaking. Technically it doesn't make sense to keep the image in color: since IR are next to the red channel, the only overlap should be on the red channel. But since the image contains some information through the other channels, why not use it ? So the third image shows a result in arbitrary colors. I chose to keep it rather neutral, but like I wrote, it's completely arbitrary.