This photograph was part of an experiment. I took a nearly identical photo of the same plant in color as well. By comparing the differences between the color and infrared prints as well as a black & white print made from the color print, I learned a lot about how different infrared photography is from that in the visible spectrum.

 

 

There's a bit of a deep dive here, so you can skip the rest if you're not interested.

 

The most obvious change is the color of the leaves in the plant. I picked this setting very deliberately to isolate the leaves. The leaves are all green except the closest one (lower-center, pointing down to 5 o'clock). That one is red. Obviously, they are all identical here.

 

It makes sense. Color is a visible spectrum thing. An infrared camera doesn't see any appreciable level of visible spectrum light - it's eliminated by a special filter over the chip just as a regular camera eliminates infrared by a special filter over the chip.

 

But there's more to it than that, because the brightness of the leaves is really dramatic. As the time this photo was taken, the leaves were primarily in sunlight, although feathering off towards the ends of the back leaves. These leaves are all pretty consistently hot. That is, they appear to be emitting more infrared than they are reflecting leading to the completely flat, but bright look.

 

Look at the stalk of the plant. Halfway up, it passes from sunlight to shadow. Look at the difference in the tone of the stalk. In a digital photo, this would have a much higher contrast. Either the sunlight part of the stalk would be flat white and there'd be detail in the shady part, or there'd be detail in the sunny part and the rest of the picture would be really dark, with the stalk in shade going to black.

 

Notice too, how you can see detail all around the background of the photo. Again, normally, in order to capture detail in the leaves, the background would fade to black in many places, but here there is detail throughout.

 

Interestingly, the ring of lichen on the bottom left (and to a lesser extent, the one on the right) has a different tonal relationship to the rock in infrared. It is much more visible and contrasty enough to be used as part of the composition - not really possible in color or b&w.

 

Finally, there are the branches to the right of the stalk flowing down from the rock over the side. An extremely interesting capability of infrared is that you don't get blown-out highlights from sunlight at a point like this. These branches were a pale brown color, but the sun hit them at an angle that caused a lot of glare and a big specular highlight. In infrared, there is clean detail throughout. More importantly, the amount of background infrared radiation available seems more consistently placed than visible light in a regular photo. What I mean is that you can preserve detail from highlights and shadows much more easily in infrared. The problem is that there are occasionally very, very bright objects (like leaves) that you'll have to figure out how to expose for.