A medium format 6x7cm film SLR system that offered high quality performance, handling convenience and versatility required for professional photography. It consisted of 3 models of the RB67 series:
- RB67 Professional - the world's first medium format 6x7cm SLR with unique built-in revolving back and bellows focusing;
- RB67 Professional S - a model with minor changes like orientation indicator for portrait or landscape mode on the rotating back, a new method of multiple exposure prevention, and a new focusing knob lock;
- RB67 Professional SD - a model with support of the 6x8cm format and L series lenses with a larger mount diameter (61mm, the same as that of the RZ67). An adapter was needed to mount Non-C, NB and C-series lenses.
The RB67 series cameras were developed as complete modular system cameras, with a very high degree of interchangeability in lenses, finders, focusing screens, film holders and backs, plus a full range of other valuable accessories which permitted their use in many other day-to-day assignments. The cameras became an instant success that lasted for decades to a world-wide status as the "workhorse of the pros".
A wide range of lenses from the 37mm fisheye to the 500mm medium telephoto were available in the system, including special application lenses for Variable Soft Focus, PC shift, Variable Flat Field Macro, Zoom, and an exceptional series of K/L APO telephotos. The lens designs incorporated a Seiko #1 between-lens shutter, with the control mechanism in the main camera body, which also provided full flash synchronization at all shutter speeds up to 1/400 sec.
The lenses for the RB67 system can be divided into five series:
- The Mamiya-Sekor Non-C series - the first generation, single-coated, released along with the RB67 Professional in 1970;
- The Mamiya-Sekor NB series - the transition series produced in 1973-1974, optically identical to the Non-C series but with a new barrel design that matched the later C series;
- The Mamiya-Sekor C series - the second generation, multi-coated, released with the RB67 Professional S in 1974;
- The Mamiya K/L series - newer designs optically identical to the RZ67 series lenses, compatible both with RB67 Professional / RB67 Professional S cameras (code "K") and later RB67 Professional SD camera (code "L"). These lenses mounted directly to RB67 Professional / RB67 Professional S cameras without an adapter. Mounting on the RB67 Professional SD camera required removing a ring adapter from the back of the lens;
- The Mamiya L series - compatible with the RB67 Professional SD only. Only two models were released: SHIFT L 75/4.5 S/L and APO L 500/6 L.
Design emphasis was placed on high resolving power and excellent color balance justifying the 6x7cm format. A multi-coating process made the Mamiya-Sekor lenses among the sharpest in the world. It eliminated reflection over a wide range of frequencies, making images clearer and tones crystal clear. In color work this was especially valuable as color rendition was vastly improved.