
Pentax introduced the Program A (or Program Plus in North America) in 1984. It is a manual-focus 35 mm SLR camera.
It has four exposure modes, selected using a dial around the shutter release and the lens' aperture ring:
- Programmed automatic exposure (KA lenses only): lens aperture set to 'A', shutter dial set to 'Auto'
- Aperture-priority AE (K, Kf or KA lenses): lens aperture set to a value, shutter dial set to 'Auto'
- Metered manual exposure: Lens aperture set to a value, shutter dial set to 'Man'. Even 42 mm screw-mount lenses can be used for manual exposure, with a screw-to-K-mount adapter ('Mount Adapter K'). With screw-mount lenses, stopped-down metering is used.
- Programmed flash: lens aperture set to 'Auto' for programmed flash with a KA lens, or to a value for normal auto flash with any other lens. Shutter dial set to 'Auto' with dedicated flashes, or '100' for others.