PEN

The PEN EE ("Electric Eye") Series featured a built-in meter and automatic exposure (AE). The first model, the EE, used a simplified AE: there was only one shutter speed (1/60) and the aperture was selected by the camera.
On the later models two shutter speeds were available: 1/200 for AE and 1/40 intended for flash exposure with manual selectable apertures (also allowing manual exposure). The first models used a selenium meter round the lens, later models used a CDS cell in the camera.
Lens design was also changed on the various models. The original EE used a 28mm/F3.5, the EE-S had an 30mm/F2.8, the EM had a 35mm/F2 and the EE-D featured a fast 32mm/F1.7 lens next to Program Exposure (!).
The EM was a motorized model, the EF had a built-in flash.
The Rapid EE-D and EE-S were outsider models: they took the AGFA half-frame Rapid film cassettes instead of standard 35mm film.