46x34x18cm The RB67 is a highly expandable interchangeable medium format single-lens reflex camera, with interchangeable lenses, finders, focusing screens, film winders, and film holders. There are three generations: the RB67 Professional (first released in 1970), the RB67 Pro-S (released in 1974), and the RB67 Pro-SD (released in 1990). The RB67 Professional was introduced in 1970 with an appearance similar to conventional medium format single-lens reflex cameras like the Hasselblad, but with a unique 6x7 cm format, which is closer to the typical 8x10 inch aspect ratio for portraits. This was because it was primarily intended for studio use [1]. Therefore, the brochures at the time touted it as "the world's first medium format camera to adopt the ideal ratio (6x7cm) for (portrait) photography." While there were some competitors from other companies, this camera was the first medium format single-lens reflex camera to feature a bellows focusing mechanism and a revolving back. Furthermore, the adoption of a lens shutter provided the advantage of full flash synchronization. It was originally created to complement the Mamiya C series and the Mamiya Press. Although it is much larger and heavier than other medium format single-lens reflex cameras at the time, this is due to the inclusion of conventional professional features such as a rack-and-pinion focusing mechanism and a revolving back. The name RB stands for "Revolving Back" [2], referring to the revolving mechanism that allows for instant switching between horizontal and vertical orientation of the frame by rotating the film holder by 90 degrees. The Mamiya RB67 is a professional 6x7cm single-lens reflex camera manufactured by Mamiya Kōki Seisakusho. It is characterized by the adoption of a revolving mechanism that allows for easy switching between horizontal and vertical frame orientation. (RB stands for Revolving Back). Although primarily designed for studio use, it can also be used outdoors.