Charles Malveaux brought a very big model airplane to the Public Lab Barnraising last week, and programmed it to fly around and take infrared photos. Charles is a research engineer and graduate student at Louisiana State University studying the use of UAVs to monitor sugar cane and other crops. The UAV Charles flew was a model Piper Cub with a wingspan of about five feet. .
Charles controlled the plane manually as it taxied and then took off from the ground. Then he transferred control to the onboard computer to fly a pattern and take 12 photographs in a grid. Landing was manually controlled.
Four photos taken by the IR converted Canon S100 onboard the model Piper Cub. Shutter speeds (L to R from upper left) are 1/640, 1/640, 1/1000, and 1/400.
I think the IR block filter in the Canon S100 had been replaced with a Schott BG3 glass filter, or something very similar. Charles purchased the converted camera from Event 38, and that seems to be what they are selling. But the photos above are direct from the camera with no post processing, which is very confusing. These photos resemble false color IR images which require swapping channels after the photos are transferred to a computer. So I am not sure how the images where produced.
I also don't know how the exposure was being determined for each photo. The shutter speed varies among photos from 1/160 to 1/1250 second, with the ISO (800) and aperture (f/2.0) remaining constant. Only a few of the photos are free of motion blur. The sun was setting during the flight and it was very windy, so conditions were not ideal for this kind of photography.
I would be interested to learn whether a CHDK script was running in the camera during the flight, and what the white balance settings were. And more generally, How can these reddish photos be produced without post processing?