Guide number

Abstract: The object distance from a range finder is factored into the guide number of the strobe to obtain an aperture value in binary form by a decoder. As the size of aperture opening of the shutter is increasing from the minimum to the maximum, a counter counts up a corresponding number of pulses in addition to the preset value of film speed. The output of the counter is compared with the output of the decoder by a comparator upon coincidence to produce an actuating signal for the strobe.

Abstract: An amount-of-light-emission control data for controlling the amount of light-emission is corrected so that the amount of strobe light-emission becomes proper. In the adjustment process after manufacturing a digital still camera, a subject is placed in a predetermined position, and is photographed by determining a predetermined guide number GN. A guide number GN corresponding to the amount of light-emission of a strobe 45 is calculated from a video signal obtained by the photography. The predetermined actual guide number GN and the guide number GN corresponding to the actual amount of light-emission are compared with each other, to correct the value of control data for determining the amount of light-emission so that there is no difference therebetween. The corrected or updated value of control data in which the predetermined updated corrected guide number GN and the guide number GN corresponding to the actual amount of light-emission are approximately equal to each other is stored in a memory 6. At the time of actual photography, the updated corrected value of control data is read out from the memory 6 in conformity with the updated corrected guide number GN, and the data read out is applied to an amount-of-light-emission control circuit 30, so that a strobe flash is fired.

Abstract: Under exposure determination unit 212 determines whether or not there is under exposure during exposure set using a hand vibration time limit. When a suitable exposure time is longer than the hand vibration time limit, the exposure time is increased by increasing the gain set for the hand vibration time limit. When a flash is used, the distance the emitted light of the flash must reach is determined from the flash guide number and open aperture value, and a determination is made as to whether or not the light emitted by the flash will reach the photographic subject. Under exposure is determined when the distance to the photographic subject is longer than the distance attained by the light emitted from the flash, and the gain is adjusted in accordance therewith.

Abstract: A camera system with function of automatically coordinating flash intensity includes a lens, an image sensor, a focus system, a focus sensor and a control unit. The lens is capable of controlling light amount that entrance into camera. The focusing system is capable of driving the lens to focus thereby forming a clear image on the image sensor. The focus sensor is capable of sensing first step information of the focusing system during the focusing process, and sending the information to a control unit. The control unit is capable of transforming the result of the focusing system to a distance that the object apart from the camera, and configures out the guide number with the aperture number thereby calculating the flash intensity. The present camera systems without neither a professional measurement tool nor an additional pre-flash may measure the distance that the objects apart from the camera, and low down the cost and power consumption. The camera systems may also precisely control the flash intensity thereby coordinating the exposure effect.