This is an Olympus Pen F, a single lens reflex camera that shoots 18mm x 24mm half-frame on regular 35mm film. The Pen F is part of the Olympus Pen series of
Olympus Pen F (1963) - mike eckman dot com
Olympus Pen EE-S (1962) - mike eckman dot com
My Three Half Frame Cameras - Canon Demi, Konica EYE, Olympus Pen EES
Camerosity Mike Eckman
Olympus Pen F Camera Decision Reliable Quality
Mike Eckman Dot Com - mike eckman dot com
Olympus PEN-F: back to the 1960's, with no 4K video by Jose Antunes - ProVideo Coalition
The Online Photographer: The Original Olympus Pen Half-Frame Camera
Leica Archives - mike eckman dot com
Olympus Pen F (1963) - mike eckman dot com
Episode 63: Mount Olympus