Plants and infrared light


in Geek stuff, Photography, Science, The outdoors

If you have ever seen plants photographed using infrared film, you will know that they have a weird glowing quality when viewed at those wavelengths.

Apparently, the reason behind this has to do with quantum mechanics and photosynthesis. Photons with shorter wavelengths (violet and beyond) have higher energy than those with longer wavelengths (red and beyond, in the other direction). Since only photons with a certain level of energy can be used by photosystems I and II in chloroplasts, plants reflect insufficiently energetic photons, rather than absorbing them. This keeps them from taking in uselessly low energy photons which would simply turn into heat, rather than powering their photosynthetic machinery.

{ 2 comments… read them below or add one }

coyote February 21, 2009 at 8:53 am

I used to use IF B&W semiregularly. Loved the pale leaves… and the daylight skies that gradated kind of eerily from pale gray at the horizon to intensely black overhead… the results were worth the headache of composing through a dark red filter.

Milan February 21, 2009 at 7:54 pm

I only tried IR film once – shooting night scenes with a photographer from Victoria. Unfortunately, something went wrong with the roll I used and it was completely fogged.

It would probably be worth trying again, when I am in the mood to shoot film.

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