> Long before the final assembly I'd wired the little LED under the viewfinder to one of the pi's GPIO. I'm not sure what it originally represented...
From the manual[1, 2]:
When you are not using flash, a red light may appear under the viewfinder as you begin to press the shutter button. It warns that the lighting on the scene is not bright enough for picture taking without a tripod or other firm support.
Also, this bit from the manual is somewhat amusing given the extraordinary chain of events occurring inside the hacked camera:
As you begin to press the shutter button, your camera releases sound waves to the central part of the scene. The frequencies are far beyond our range of hearing and travel at the speed of sound. The split second it takes for the sound to reach your subject and the echo to return is fed into a tiny electronic computer inside the camera. The computer uses this time measurement to calculate the distance between the camera lens and your subject, then signals a motor to turn the lens until your subject is in sharp focus. This extraordinary chain of events takes place in less than 1/3 of a second.
From the manual[1, 2]:
When you are not using flash, a red light may appear under the viewfinder as you begin to press the shutter button. It warns that the lighting on the scene is not bright enough for picture taking without a tripod or other firm support.
Also, this bit from the manual is somewhat amusing given the extraordinary chain of events occurring inside the hacked camera:
As you begin to press the shutter button, your camera releases sound waves to the central part of the scene. The frequencies are far beyond our range of hearing and travel at the speed of sound. The split second it takes for the sound to reach your subject and the echo to return is fed into a tiny electronic computer inside the camera. The computer uses this time measurement to calculate the distance between the camera lens and your subject, then signals a motor to turn the lens until your subject is in sharp focus. This extraordinary chain of events takes place in less than 1/3 of a second.
[1] http://www.cameramanuals.org/polaroid_pdf/polaroid_sonar.pdf
[2] Found via http://butkus.org/chinon/ which itself is a lovely 1990's style web-site. I couldn't help but donate $3.