GB344900A - Improvements in and relating to photographic printing - Google Patents

Improvements in and relating to photographic printing

Info

Publication number
GB344900A
GB344900A GB2754029A GB2754029A GB344900A GB 344900 A GB344900 A GB 344900A GB 2754029 A GB2754029 A GB 2754029A GB 2754029 A GB2754029 A GB 2754029A GB 344900 A GB344900 A GB 344900A
Authority
GB
United Kingdom
Prior art keywords
cell
condenser
light
negative
valve
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.)
Expired
Application number
GB2754029A
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.)
Cambridge Instruments Ltd
Original Assignee
Cambridge Instruments 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 Cambridge Instruments Ltd filed Critical Cambridge Instruments Ltd
Priority to GB2754029A priority Critical patent/GB344900A/en
Publication of GB344900A publication Critical patent/GB344900A/en
Expired legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
    • G01J1/4209—Photoelectric exposure meters for determining the exposure time in recording or reproducing
    • G01J1/4219—Photoelectric exposure meters for determining the exposure time in recording or reproducing specially adapted for enlargers

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Projection-Type Copiers In General (AREA)

Abstract

344,900. Photographic printing. CAMBRIDGE INSTRUMENT CO., Ltd. and MOSS, E. B., Chesterton Road, Cambridge. Sept. 10, 1929, No. 27540. [Class 98 (i).] The automatic control of exposure in photographic printing is effected by regulating the quantity of light incident upon a print from the negative by causing some or all of it to fall upon a photo-electric cell, and using the activation of the cell to control the charging of a condenser of known capacity, the voltage of which is transferred to the grid of a three-electrode valve, the current being utilized to operate delay apparatus to close a shutter or cut off the light. The apparatus may be used in connection with the automatic production of uniformly exposed photographic prints from negatives of varying density. The anode 1 of a photo-electric cell 2 is connected to the positive end of a high tension supply 3 together with the anode 4 of a three-electrode valve 5. The negative terminal 6 of the cell 2 is connected to the grid 7 of the valve and to one side of the condenser 8 of known capacity. The other terminal of the condenser is in the negative lead of the low tension supply, from which the grid 7 of the valve is insulated except when contact is made by a key 9. The anode current is used to operate the relay 11 and is adjusted to zero with key 9 depressed. If the key 9 be lifted when light is incident on the cell 2 the condenser 8 will gradually be positively charged and the anode current will increase. A portion of the light from a light source 13 after passing through a negative 15 on its way to the print 18 is deflected by a semi-transparent mirror 17 on to the photo-electric cell 2, Fig. 3.
GB2754029A 1929-09-10 1929-09-10 Improvements in and relating to photographic printing Expired GB344900A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB2754029A GB344900A (en) 1929-09-10 1929-09-10 Improvements in and relating to photographic printing

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2754029A GB344900A (en) 1929-09-10 1929-09-10 Improvements in and relating to photographic printing

Publications (1)

Publication Number Publication Date
GB344900A true GB344900A (en) 1931-03-10

Family

ID=10261238

Family Applications (1)

Application Number Title Priority Date Filing Date
GB2754029A Expired GB344900A (en) 1929-09-10 1929-09-10 Improvements in and relating to photographic printing

Country Status (1)

Country Link
GB (1) GB344900A (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE767288C (en) * 1939-03-01 1952-04-15 Walter Luehrig Magnification device with photoelectric light meter
DE1156643B (en) * 1956-06-26 1963-10-31 Voigtlaender Ag Device for automatic exposure control
DE1158361B (en) * 1954-03-01 1963-11-28 Agfa Ag Photographic device with a photoelectric light measuring or control device
DE1206304B (en) * 1959-10-02 1965-12-02 Agfa Ag Photographic camera with a central shutter and an exposure control device
DE1241259B (en) * 1960-09-24 1967-05-24 Photokino G M B H Recording camera with built-in exposure metering or regulating device
US4350438A (en) * 1976-06-03 1982-09-21 Hoechst Aktiengesellschaft Light dosing device

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE767288C (en) * 1939-03-01 1952-04-15 Walter Luehrig Magnification device with photoelectric light meter
DE1158361B (en) * 1954-03-01 1963-11-28 Agfa Ag Photographic device with a photoelectric light measuring or control device
DE1156643B (en) * 1956-06-26 1963-10-31 Voigtlaender Ag Device for automatic exposure control
DE1206304B (en) * 1959-10-02 1965-12-02 Agfa Ag Photographic camera with a central shutter and an exposure control device
DE1241259B (en) * 1960-09-24 1967-05-24 Photokino G M B H Recording camera with built-in exposure metering or regulating device
US4350438A (en) * 1976-06-03 1982-09-21 Hoechst Aktiengesellschaft Light dosing device

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