A medium format 6x6cm film SLR system that offered high quality performance, handling convenience and versatility required for professional photography. It consisted of 5 models of the SQ series:
- SQ - the first camera of the system, with interchangeable lens, film back, finder and focusing screen systems;
- SQ-A - a model with mirror lockup and a new viewfinder system now supporting auto exposure;
- SQ-Am - a version of the SQ-A designed exclusively for motorized operations;
- SQ-Ai - a slightly updated SQ-A with support of bulb mode and longer shutter speed of 16 sec., OTF metering and the ability to use a dedicated motor drive (not compatible with the rest of the SQ series cameras);
- SQ-B - a simplified version of the SQ-A with basic mechanical features only: the camera did not activate the metering capability even with the AE finder, and the film advance was manual only.
The SQ series cameras were developed as complete modular system cameras, with a very high degree of interchangeability in lenses, finders, focusing screens, film backs, plus a full range of other valuable accessories which permitted their use in many other day-to-day assignments, requiring a fast-handling camera with complete exposure automation. They offered the handling speed of the 35mm camera, but with the advantage of the 6x6cm frame size.
A wide range of lenses from the 35mm fisheye to the 500mm medium telephoto, plus macro and zoom lenses, were available in the system. The very compact lens designs incorporated a Seiko #0 between-lens shutter, with the electronic control mechanism in the main camera body, which also provided full flash synchronization at all shutter speeds up to 1/500 sec.
The ZENZANON lenses for the Bronica SQ system can be divided into two series:
- The S series - the first generation, with their orange-colored "Line of Distinction", great resolving power and superior image quality;
- The PS series - the next generation that took full advantage of MTF technology in their design, and had overall improvement in optical performance.
A number of S and PS-series models were also designed and produced by Schneider-KREUZNACH in Germany.
Regardless of generation and manufacturer, all ZENZANON lenses for the Bronica SQ system cameras were noted for their high image depiction characteristics and superior color balance.
In 1995, lens manufacturer Tamron acquired the Bronica camera business. A new SQ-B camera and three new PS lenses were soon introduced, however, with the advent of digital photography, medium format sales declined at a rapid pace, and for Bronica, that slip was faster since their core customer base - portrait and wedding photographers - adapted well to digital SLR equipment. On October 1, 2004, Tamron announced the worldwide discontinuation of Bronica SLR cameras and accessories as of October 31, 2004.