Automatic exposure control

Claim 1

IN COMBINATION IN A PHOTOGRAPHIC CAMERA HAVING A FILM EXPOSING APERTURE, DIAPHRAGM MEANS FOR ADJUSTING THE RELATIVE AMOUNT OF LIGHT REACHING SAID APERTURE COM PRISING A PAIR OF IRIS BLADES HAVING COOPERATING EDGES ARRANGED TO DEFINE AN ADJUSTABLE LIGHT OPENING THERETHROUGH IN LINE WITH THE OPTIC AXIS OF SAID APERTURE, A PAIR OF ARMS EACH SUPPORTING ONE OF SAID IRIS BLADES AT ONE END THEREOF, EACH OF SAID ARMS BEING MOUNTED INTERMEDIATE ITS ENDS FOR PIVOTAL MOVEMENT IN A PLANE SUBSTANTIALLY NORMAL TO THE OPTIC AXIS OF SAID APERTURE, THE PIVOT POINTS OF SAID ARMS, BEING SPACED FROM ONE ANOTHER AND AT DIFFERENT DISTANCES FROM SAID OPTIC AXIS OF SAID APERTURE, AND MEANS FOR ENGAGING THE OPPOSITE ENDS OF SAID ARMS TO ANGULARLY SHIFT THE SAME, THE RATIO OF THE DISTANCES FROM THE PIVOT POINT OF ONE OF SAID ARMS TO ITS OPPOSITE END AND TO SAID OPTIC AXIS BEING SUBSTANTIALLY THE SAME AS THE RATIO OF THE DISTANCES FROM THE PIVOT POINT OF THE OTHER OF SAID ARMS TO ITS OPPOSITE END AND TO SAID OPTIC AXIS, SAID ENGAGING MEANS BEING A ROTATABLE PINION AND SAID OPPOSITE ENDS OF SAID ARMS BEING IN THE FORM OF GEAR RACKS MESHING WITH SAID PINION.