Illuminating control arrangement for photographic cameras

Abstract

Abstract AN ARRANGEMENT FOR ADAPTING FLASH EQUIPMENT IN PHOTOGRAPHIC CAMERAS TO DAYTIME USE AS WELL AS NIGHTTIME CONDITIONS. TWO TRANSISTORS HAVE THEIR EMITTERS CONNECTED TOGETHER AND ARE, IN TURN, CONNECTED TO A SINGLE SOURCE OF CURRENT. THE BASE-EMITTER PATH OF ONE TRASISTOR INCLUDES A LIGHT SENSOR FOR THE PURPOSE OF CONTROLLING THE TRANSISTOR AS A FUNCTION OF THE PREVAILING LIGHT CONDITIONS. THE SECOND TRANSISTOR INCLUDES A VARIABLE RESISTOR IN ITS BASE-EMITTER PATH, WHICH IS SET IN ACCORDANCE WITH THE OBJECT DISTANCE. THIS SETTING OF THE VARIABLE RESISOR PRODUCES CONTROL OF THE DIAPHRAGM OF A CAMERA TO THEREBY LIMIT THE AMOUNT OF LIGHT RECEIVED BY THE FILM FROM THE OBJECT TO BE PHOTOGRAPHED AS A FUNCTION OF THE APPLICABLE GUIDE NUMBER. EACH COLLECTOR OF THE TWO TRANSISTORS INCLUDES AN INDICATING LAMP IN ITS CIRCUIT SO AS TO PROVIDE A VISUAL INDICATION OF THE CURRENT OR CONDUCTING STATE OF A TRANSISTOR. THE COMBINED ACTION OF THE TWO TRANSISTORS IS SUCH THAT AS THE PREVAILING LIGHT INTENSITY DECREASES THE TRANSISTOR ASSOCIATED WITH THE VARIABLE RESISTOR BECOMES INCREASINGLY CONDUCTIVE.

Inventors

• 👤 Dieter Engelsmann
• 👤 Gunter Pawlik

Bibliographic Details