PHOTOMETER

• Main Authors: TAGUCHI T,JA, MASHIMO Y,JA, UCHIYAMA T,JA
• Format: Patent
• Language: English
• Published: 17.12.1974
• Subjects: ACCESSORIES THEREFOR; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USINGWAVES OTHER THAN OPTICAL WAVES; APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FORPROJECTING OR VIEWING THEM; CINEMATOGRAPHY; COLORIMETRY; ELECTROGRAPHY; HOLOGRAPHY; MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT,POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRA-RED,VISIBLE OR ULTRA-VIOLET LIGHT; MEASURING; PHOTOGRAPHY; PHYSICS; RADIATION PYROMETRY; TESTING

A camera is provided with a photometer capable of indicating the necessity of switching from a natural light exposure mode to a flash exposure mode or of automatically switching from the natural light exposure mode to the flash exposure mode, when the brightness of a portion of the field of view containing the object to be photographed becomes lower than that of the remaining field of view by more than a predetermined difference, regardless of the general level of brightness. There are two photosensitive elements, one for a central field containing the object, and the other for the remainder of the field of view and they are connected in series to provide a different signal at their junction which is then compared with a fixed voltage to determine whether the object field is sufficiently below the background in brightness to require an aiding flash for proper exposure. A succession of switching steps take place on the actuation of the shutter release button, the above mentioned comparison being performed on the first step. On the second step the same comparator is used to determine whether the level of brightness detected by one of the photosensitive elements is so low that flash photography is required even though not called for by the first step comparison. At subsequent steps one of the photosensitive elements is used to control the exposure by setting the aperture or the exposure time.