Try to put yourself in the place of an engineer tasked with building a camera in 1961. Your specs include making it easy to operate, giving it automatic exposure control, and, oh yeah — you can’t use batteries. How on Earth do you accomplish that? With a very clever mechanism powered by light, as it turns out.
This one comes to us from [Alec Watson] over at Technology Connections on YouTube, which is a channel you really need to check out if you enjoy diving into the minutiae of the mundane. The camera in question is an Olympus Pen EES-2, which was the Japanese company’s attempt at making a mass-market 35-mm camera. To say that the camera is “solar-powered” is a bit of a stretch, as [Alec] admits — the film advance and shutter mechanism are strictly mechanical, relying on springs and things to power them. It’s all pretty standard camera stuff.
But the exposure controls are where this camera gets interesting. The lens is surrounded by a ring-shaped selenium photocell, the voltage output of which depends on the amount of light in the scene you’re photographing. That voltage drives a moving-coil meter, which waggles a needle back and forth. A series of levers and cams reads the position of the needle, which determines how far the lens aperture is allowed to open. A clever two-step cam allows the camera to use two different shutter speeds, and there’s even a mechanism to prevent exposure if there’s just not enough light. And what about that cool split-frame exposure system?
For a camera with no electronics per se, it does an impressive job of automating nearly everything. And [Alec] does a great job of making it interesting, too, as he has in the past with a deep-dive into toasters, copy protection circa 1980, and his take on jukebox heroics.