Innovations in 35mm SLR Camera Design: 1940 to 1960
The first innovation of this 20-year period came in 1947, in the form of the ambitious but highly unreliable Hungarian Gamma Duflex. This was the earliest SLR camera to use an instant return mirror, and an internal semi-automatic lens diaphragm. Previously, reflex mirrors had been coupled to the shutter release and were spring actuated so that they rose automatically when the shutter was tripped, but this meant the viewfinder remain blacked-out until the mirror was manually reset to its original position. Similarly, lens diaphragms also had to be manually closed to the required f-stop before exposure, and opened afterward. The moment before and after exposure was often a period of dim visibility. The Duflex's semi-automatic diaphragm closed the lens diaphragm to a pre-set f-stop when the shutter was released, but it still needed to be manually re-opened after exposure. In 1948, the Italian Rectaflex introduced the world to the first Pentaprism SLR, although its ey...