Photographing apparatus
AssigneeOlympus Optical Co., Ltd.
InventorsMamoru Aihara, Yutaka Takahashi, Yoshio Nakajima, Tsuyoshi Matsuura
Life of this patent
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Abstract
A photographing apparatus employs a real time photometry technique, and includes a central processing unit to which information concerning the characteristic of a film such as a film speed and other information relating to photographing conditions are supplied through input means. The central processing unit selectively controls the connection of integrating capacitors in an integrating circuit on the basis of such input information, and accurately derives an expected exposure period and the remainder of the exposure period. Also, a display of various information is permitted.
Claims20
A photographing apparatus comprising:
- a photoelectric conversion circuit including a photoelectric transducer element which continuously determines the brightness of an object being photographed for producing an output signal which corresponds to the brightness of the object;
- means for sequentially calculating an expected exposure period during the course of a photographing operation in response to said output signal from the photoelectric conversion circuit;
- means for determining an equivalent exposure period from the initiation of the photographing operation to the instant when the expected exposure period has been determined, means for subtracting said equivalent exposure period from said expected exposure period calculated by the calculating means to derive the remainder of the exposure period in a sequential manner;
- means for displaying said remainder of the exposure period during said photographing operation;
- and
- a shutter drive circuit for opening a shutter at the initiation of the photographing operation and for closing the shutter when the remainder of the exposure period is substantially zero.
A photographing apparatus comprising:
- means for determining the brightness of an object being photographed and for producing an output signal which corresponds to the brightness of said object utilizing direct photometry;
- means for periodically calculating an expected exposure period while an exposure operation is taking place in response to said output signal;
- said calculating means including an integrating circuit including a plurality of integrating capacitors which are selectively switched in and out of said integrating circuit for changing the integrating rate of said output signal;
- and
- a shutter drive circuit for opening a shutter at the initiation of the photographing operation and for closing said shutter at the end of said expected exposure period.
A photographing apparatus, comprising:
- first means for generating a signal during an exposure period which is a function of the brightness of an object being photographed and the light received by said first means, responsive to a shutter opening;
- second means for providing a reference voltage;
- integrating means for integrating said signal;
- said integrating means including means for changing the rate of integration of said signal at any time during said exposure period in response to the light received by said first means;
- comparator means for comparing said integrated signal against said reference voltage to generate an output;
- and
- a shutter drive circuit for closing the shutter to provide a proper photographing operation responsive to said comparator output.
A method for determining the time for a proper photographing interval to operate a shutter, comprising the steps of:
- providing a reference voltage level;
- during an exposure period, generating a signal representative of the light being reflected from the object being photographed, responsive to the opening of said shutter;
- integrating said signal at a first predetermined rate during said exposure period;
- integrating said signal at a second predetermined rate during said exposure period;
- comparing said integrated signal with said reference voltage;
- and
- closing said shutter in response to the output of said comparison operation.
A photographing apparatus including a shutter, comprising:
- first means for generating a signal which is a function of light received by said first means from the object being photographed, responsive to a shutter opening;
- second means for providing a reference voltage;
- means for periodically calculating an expected exposure period and the remainder of said exposure period during an exposure operation in response to said signal;
- said calculating means including integrating means for integrating said signal at two or more selected rates to reach said reference voltage before the time said shutter should be closed for a proper exposure period;
- and
- means responsive to said selected integration rates for closing said shutter when the remainder of the exposure period is substantially zero.
A method for determining the time for a proper photographing interval to operate a shutter comprising the steps of:
- providing a reference voltage level;
- generating a signal representative of the light being reflected from the object being photographed, responsive to the opening of said shutter;
- periodically calculating an expected exposure period and the remainder of said exposure period during an exposure operation in response to said signal;
- said calculating step including integrating said signal at two or more selected rates;
- and
- closing the shutter at a time after the integrated signal reaches the reference voltage level, which time is when the remainder of the exposure period is substantially zero.
Dependencies are inferred from the claim text.