The first camera by Simmon Bros was produced for the US Signal Corps in 1944-1945. The PH-501/PF was designed as a camera with a cast magnesium body of rugged construction for taking 2¼” x 3¼” still pictures under combat conditions. The use of a magnesium body meant that the camera was both light-weight, but also eminently suited for use in the tropics, and the absence of a bellows meant that the unit was more rugged than the standard combat Graflex.
The camera was first produced in November 1944 and entered service in December 1944. It seems that the camera was designed for and primarily used by the U.S. Signal Corps. The camera production ceased with the end of World War II in late 1945. Based on observed serial numbers, less than 200 cameras were ever built. The camera has a curtain-type, vulcanized rubber cloth focal-plane shutter with the following six shutter speeds: 1/25, 1/50, 1/100, 1/200, 1/400 and 1/800 second. In addition, the shutter can be set for time and flash exposures.
Lenses for the camera were the (standard) f=101mm 1:4.5 Wollensak Velostigmat and the f=225mm 1:6.3 Ilex Paragon, both with a 58mm screw mount. When the camera is not in use, the 101mm lens is fully protected by the fold-down viewfinder hood.
To operate the camera, one first had to set the f-stops and distance, after which the speed had to be set. Borrowing in concept from other military cameras, such as the Fairchild F-8, the shutter speed is driven by spring tension. Once the tension knob had been fully wound, shutter curtain could be wound, with the speeds appearing in a window. The process was to wind the shutter curtain to the desired speed. Alternatively, one could wind the shutter curtain to 1/800th, and then press the curtain release lever, which would set the shutter sped to 1/200th. A second press would reduce the shutter speed to 1/50th.