Big Low near Infra-red.

In the old days you could get infra-red sensitive film and by using the IR focus setting on a relflex camera's lens you could take what is known as near infra-red pictures. Today with the modern digital camera you can either buy a ready made IR camera or have the hot mirror removed from your existing camera to allow you to use a IR filter over the lens to take IR images and be able to hand hold the camera. You can use a non converted camera and the filter but this would mean you having to tripod mount the camera to get the required exposure. I have a Canon Powershot A640 which has had the mod done. The images below have been processed by swapping the red and blue channels this enhances the image.

So what use are these images other than giving a snowy effect.Well particularly in archaeology, the effect ehances vegetative growth. The health of a plant depends on its root system and if a plants root system is restricted by poor soil for various reasons the plant will reflect this in its above ground growth. An example of a plant's root system being restricted is where man made underground structures, roads, walls etc have been in times past. The plant will create a pattern not always easily observed when viewed in normal colour but in infra red the plant will reflect infrared according to its health. This results in providing us with an outline for example of a building.

The images here don't really show any of this but in some you can see faint tracks across the grass which would not be that obvious.