jerryc41 wrote:
I saw this on Technology Connections on YouTube. A guy took apart an old Olympus EE (electric eye) camera to show how it works without batteries. It's very clever.
Basically, there is a light meter inside, and that tiny swinging needle controls several moving parts inside that set the aperture. Take a look if you want to see some ancient, clever engineering - without batteries.
THIS IS THE LINK.