A Minolta AF-C landed on my doorstep today. It’s a tiny little thing, no bigger than a Contax T, which is one of the smallest 35mm cameras ever made. Why does the f/2.8 lens have so many elements (6) for a compact? How do they run an AF system off four button batteries? How did they get this thing so small?
The thumb wheel film advance also cranks the lens backward toward infinity, against a spring. Even then, it looks like only the rear group moves. Releasing the shutter lets the lens jump forward to the position selected by the active AF. Then when you wind to the next frame, the lens returns to its “ready” position. It’s a lot like how cameras like the Konica Autoreflex T could run AE off two 675 cells – all of the mechanical work is done by springs, regulated at a place where a tiny amount of mechanical leverage can arrest great forces.