Visible and Invisible

Woo Hoo - back in the Midwest for a visit to "Ketelsen East"! But what is this watery substance my skin is excreting??? For the first time the last few Summer visits, it is miserably hot and humid! A big change evidently as they have been "enjoying" a cool, very wet Spring. Farmers have been unable to get into fields to plant and evidently a slow-motion disaster is in progress...

Anyway, last weekend my maternal grandmothers family held a reunion that I was able to attend! Held every 2 years, it has been going on a few times. Held in a church camp in eastern Iowa (Grace Lutheran Church Camp), I didn't take any photos of relatives I've not seen in decades, but knowing that there would be some blue sky and greenery, I took my IR-modified camera to take some landscape photos!


Most modern cameras are sensitive to infrared (IR) light, but the sensors are filtered to specifically block those wavelengths invisible to the eye beyond the red end of the visible spectrum. Well, there are some neat effects going on just past our vision limits and 8 or so years ago I got an inexpensive DSLR camera on Ebay and paid a modest fee to remove the IR blocking filter and replace it with an IR pass filter. While the view through the camera looks normal, the photos are anything but! As shown here, the IR shots show white trees and grass, indicative of chlorophyll, which is a strong reflector of IR, and dark water and sky, which absorb or do not scatter IR light. Please enjoy the photo comparisons, which I've tried to match the exact field with the modified Canon 20D, and the visible color images from my Canon 6D. The IR shots do not look unlike the view of a snowfall covering grass and vegetation, but that is indeed NOT the case.


The longer IR wavelengths easily penetrate haze and dust, and are scattered less by the atmosphere. Looking at the photos above, the clouds just above the treetops are more easily seen in the IR shot as it is less affected by haze and contrast is increased. In the long-distance views from mountaintops in AZ, this effect can be used to more clearly discern distant details. But since the horizon is at most only a mile or two away in flat and tree-infested Iowa, this effect is much less. But note in these photos left and right that the algae mats growing along the water edge also glow white from chlorophyll!



For years I've tried to photograph details within the structure of a leaf, but it all glows so completely white it is hard to pick out any details. These photos are from an oak tree, and structure is clearly seen in the color image at right, but harder to discern in IR, even with severely playing with brightness and contrast. What you can see are some little spots that align with little leaf defects, perhaps insect bites or other small intrusions, that clearly show a lack of chlorophyll.

You may see more from the IR camera in coming weeks - I love seeing the normally hidden world revealed!