JPS56101130A - Photographic information leading-in circuit - Google Patents

Photographic information leading-in circuit

Info

Publication number
JPS56101130A
JPS56101130A JP379680A JP379680A JPS56101130A JP S56101130 A JPS56101130 A JP S56101130A JP 379680 A JP379680 A JP 379680A JP 379680 A JP379680 A JP 379680A JP S56101130 A JPS56101130 A JP S56101130A
Authority
JP
Japan
Prior art keywords
circuit
current
logarithmic
transistor
geometric
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP379680A
Other languages
Japanese (ja)
Inventor
Kazunori Mizogami
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Olympus Corp
Original Assignee
Olympus Optical Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Olympus Optical Co Ltd filed Critical Olympus Optical Co Ltd
Priority to JP379680A priority Critical patent/JPS56101130A/en
Publication of JPS56101130A publication Critical patent/JPS56101130A/en
Pending legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B7/00—Control of exposure by setting shutters, diaphragms or filters, separately or conjointly
    • G03B7/08—Control effected solely on the basis of the response, to the intensity of the light received by the camera, of a built-in light-sensitive device
    • G03B7/081—Analogue circuits
    • G03B7/083—Analogue circuits for control of exposure time

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Exposure Control For Cameras (AREA)
  • Indication In Cameras, And Counting Of Exposures (AREA)

Abstract

PURPOSE:To make the circuit of small-error and high-precision in comparison with the circuit using two resistances, by providing a logarithmic compressing circuit and a logarithmic expanding circuit for the purpose of leading ASA information to the shutter control circuit and the finder display circuit from one ASA information leading-in resistance. CONSTITUTION:The geometric current is flowed to transistor 36 according to the number of ASA stages set to logarithmic resistance 22 and is subjected to logarithmic compression, and the output of operational amplifier 34 becomes an arithmetic current. Operational amplifier 40 adds the logarithmic compressed value of the light current of display light receiving element 42, which is provided in front of the mirror, and the output of amplifier 34 to display shutter seconds on finder display circuit 46. Meanwhile, photometry of light receiving element 24 for direct photometry is started, and the shutter is closed when the charging value of integral capacitor 28 coincides with the collector voltage of transistor 50. The collector current of transistor 50 is equal to the geometric current of transistor 36 due to current Miller circuits 36, 38, 48 and 50, and the collector voltage becomes a geometric voltage.
JP379680A 1980-01-17 1980-01-17 Photographic information leading-in circuit Pending JPS56101130A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP379680A JPS56101130A (en) 1980-01-17 1980-01-17 Photographic information leading-in circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP379680A JPS56101130A (en) 1980-01-17 1980-01-17 Photographic information leading-in circuit

Publications (1)

Publication Number Publication Date
JPS56101130A true JPS56101130A (en) 1981-08-13

Family

ID=11567148

Family Applications (1)

Application Number Title Priority Date Filing Date
JP379680A Pending JPS56101130A (en) 1980-01-17 1980-01-17 Photographic information leading-in circuit

Country Status (1)

Country Link
JP (1) JPS56101130A (en)

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