Graflex RB series B
Reflex, Rapid and Revolving...
The Graflex Revolving single lens reflex camera for 2 1/4 x 3 1/4 film. Also in 3 1/4 x 4 1/4 and 4x5 "
Revolving means: Revolving back. The Film back can be set in Landscape or in Portrait mode.
Made for sheet film holders and Grafmatic Film Holder.
The spring can be wind up from 1 to 6, where 6 is fastest shutter speed, combined with the "D" smallest slit.
A roller blind with 4 different slits combined with a "6-speed" roller-mechanism gives the Graflex RB 24 different shutter times and a "T" . "O"= open. "T"= time. A to D 1/10 to 1/1000 sec.
Diaphragm from 4,5 to 32
A solid build camera, made in the thirties and forties from the last century .
The two pages of the 1914 catalog from GRAFLEX and GRAPHIC Cameras give a good impression of the working of the Graflex Camera. "Although it’s not the same camera as the Graflex RD from the thirties, the working principle is almost the same. The great advantage that a focal plane shutter has over those of the usual type will be instantly appreciated when it is considered that the focal plane shutter permits the lens to work at its entire efficiency during the whole period of exposure. With shutters in between the lens type during only a small fraction of exposure time is the lens working at its full diaphragm opening, the remaining portion of the exposure period being used by the opening and closing of the shutter". The principle is illustrated in the two diaphragms:
The diagram illustrates an exposure with the lens diaphragm set as f 4,5. The upper row of circles shows the exposure with a Focal Plane Shutter where the lens opening remains constant through the entire period of exposure.
The lower row of circles illustrates an exposure with a shutter in between the lens. A considerable portion of the exposure is consumed in opening and closing of the shutter allowing the lens to operate at the full diaphragm opening but a small portion of the total period of exposure.