Photoelectric device for comparing different light intensities characteristic of a photographic scene

Claim 1

IN A PHOTOELECTRIC LIGHT COMPARATOR FOR COMPARING DIFFERENT LIGHT INTENSITIES CHARACTERISTICS OF A SCENE TO BE PHOTOGRAPHED, THE COMBINATION COMPRISING STRUCTURE FORMING AN ELECTRICAL CIRCUIT, LIGHT RESPONSIVE MEANS ACTUABLE TO MODIFY CURRENT FLOW IN THE CIRCUIT AS A FUNCTION OF LIGHT INCIDENT UPON SAID MEANS, OPTICAL MEANS ACTUABLE TO THE SUBJECT THE LIGHT RESPONSIVE MEANS TO A FIRST LIGHT INTENSITY CHARACTERISTIC OF THE ENTIRE SCENE TO BE PHOTOGRAPHED, AND ACTUABLE TO SUBJECT THE LIGHT RESPONSIVE MEANS TO A SECOND LIGHT INTESNITY CHARACTERISTIC OF A SELECTED PORTION OF INTEREST WITHIN SAID SCENE TO BE PHOTOGRAPHED, AN ELECTRICAL METER ASSOCIATED WITH SAID CIRCUIT AND HAVING A SCALE WITH AN INDEX MARK INTERMEDIATE THE LENGTH OF THE SCALE DESIGNATING A REFERENCE INDEX AND HAVING A VISUAL INDICATOR MOVABLE PROGRESSIVELY RELATIVE TO THE SCALE IN ONE DIRECTION IN RESPONSE TO INCREASING VALUE OF CURRENT IN THE CIRCUIT, CONCIDENCE OF THE INDICATOR AND REFERENCE INDEX DENOTING A PREDETERMINED CURRENT VALUE, THE TOTAL LENGTH OF THE METER SCALE CORRESPONDING TO A RANGE OF CURRENT VALUES THAT REPRESENTS ONLY A SMALL FRACTION OF THE NORMAL RANGE OF PHOTOGRAPHIC LIGHT INTENSITIES, AND MANUALLY VARIABLE MEANS ELECTRICALLY CONNECTED WITH SAID CIRCUIT AND ACTUABLE TO MODIFY CONTINUOUSLY THE CURRENT THEREIN, SAID VARIABLE MEANS HAVING A RANGE OF VARIATION SUFFICIENT TO PRODUCE IN THE CIRCUIT SAID PREDETERMINED CURRENT VALUE AT ANY VALUE OF SAID FIRST INTENSITY WITHIN SAID NORMAL RANGE OF PHOTOGRAPHIC LIGHT INTENSITIES, SAID METER SCALE EXTENDING IN BOTH DIRECTIONS FROM SAID REFERENCE INDEX DISTANCES AT LEAST CORRESPONDING TO THE MAXIMUM AND MINIMUM PHOTOGRAPHICALLY ACCEPTABLE VALUES OF THE RATIO OF SAID SECOND INTENSITY TO SAID FIRST INTENSITY.