Pen EES-2 (circa 1968) was part of the Olympus half frame (pen) electric
eye (EE) series, it's an automatic exposure camera with a selenium meter
around the lens. Although manual aperture settings are available for flash
you can use them for manual exposure as the camera sets the shutter speed
to 1/40 sec when not set on 'auto'. The camera is zone focusing having
four positions marked with symbols from close up (head and shoulders)
to infinity (mountain). In 'auto' mode when there's not enough light for
proper exposure a red warning mark shows in the viewfinder and the shutter
release is locked.
Car park barrier!