The Bronica engineering group developed the GS-1 with the photographer in mind: 6x7 image with capabilities of 6x6, 6x4.5, and Polaroid interchangeable backs, leaf shutter lenses, for full flash synchronization at all shutter speeds, the most compact 6x7 SLR body.
Zenzanon PG interchangeable lenses ranging from 50mm to 500mm were developed specifically for the GS-1, employing computer-aided optical design and a multi-coating technology. Incorporating the compact Seiko #0 electronic lens shutter system, the camera was made smaller and optical performance upgraded. Shutter speeds were available from 1/500th of a second to 16 seconds. The Zenzanon PG series also included tele-converters that extended the focal length of lenses from 50mm to 500mm - either 1.4 or 2 times. In addition, a bellows attachment, extension tubes, close-up lenses and a professional lens hood were also available.