minute (29.25" per second). A footage counter located near the focus knob records and shows the amount of film that has gone through the camera. It is calibrated in feet.
The shutter of the Cinerama camera (#2 to #7) is a fixed blade shutter with an opening of 165 degrees. At 26 frames per second the shutter speed with regards to exposure is approximately 1/60 of a second (1/57 of a second to be exact). Number 1 camera has a shutter opening of 151 degrees which at 26 frames per second gives a speed of 1/62 of a second.
The lens aperture are set by turning a small knob located at the top of the camera between the "A" and "B" chambers. The dial is calibrated in f/stops from f/2.8 to f/22. The zero on the dial indicates the closed position of the diaphragm. The diaphragm on all three of the lenses are connected to the one control and work simultaneously. This is the only means of setting exposure on the camera unless the camera is run at some speed other than 26 frames per second.
Since all three diaphragms are operated simultaneously it follows that the exposure for the different lenses cannot be changed on to the other in spite of the fact that the subject taken by one lens might be front lighted, that by a second side lighted, and that by the third back lighted.