Photographic enlarging exposure meters

Details Photographic enlarging exposure meters Photographic enlarging exposure meters

1978-09-20

1980-04-22

Gellner, Michael L.

Photocopying

Projection printing and copying cameras

Illumination systems or details

356443, 355 83, G03B 2778

Patent

active

041992520

ABSTRACT:
This invention relates to improvements in photographic printing exposure meters, and particularly to such a meter and having a light sensitive cell which produces an illuminance dependant electrical signal used in an electronic circuit, together with inputs of other parameters of printing density, to calculate values of printing density corresponding to the input values. The parameters inputs are related to contrast grade and speed index of photographic paper, and time duration of exposure to the illuminance given by the light sensitive cell. The meter can be used to determine what exposure time is required, for a photographic paper having a particular contrast grade and speed index, to give a particular value of printing density at the measured illuminance.

REFERENCES:
patent: 2952780 (1960-09-01), Rogers, Jr.
patent: 3049050 (1962-08-01), Thomas
patent: 3074312 (1963-01-01), Olson
patent: 3506352 (1970-04-01), Denner

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