Contrast monitor

Details Contrast monitor Contrast monitor

1987-09-18

1989-03-14

Hix, L. T.

Photocopying

Projection printing and copying cameras

Methods

355 68, G03B 2732

Patent

active

048128821

ABSTRACT:
There is described a method of determining the contrast grade of the paper to be used to print a black and white photographic negative which comprises placing a photocell in the darkest significant area of a projected negative image and noting an indication of the light received or calibrating the photocell so when the photocell receives light of the same level it will indicate this, then placing the photocell in the lightest significant area of the projected image of the negative and reducing the light reaching the photocell using graduated steps until the light reaching the photocell is of the same level as the light which reached the photocell when it was placed in the darkest significant area of the projected negative image and noting the step employed to achieve this equivalence and selecting the contrast grade of the paper which is indicated by the step which achieved equivalence. The method can be performed using an enlarger or by use of a modified light exposure meter.

REFERENCES:
patent: 2411486 (1946-11-01), Weisglass
patent: 3647297 (1972-03-01), Van Westering
Article "Enlarger Analyser" Wireless World, vol. 86, No. 1531, p. 91, Mar. 1980.
Labortechnik Brochure--Jobo, Comparator 2, printed in Germany, 12/86.

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