Filter head

Details Filter head Filter head

1979-11-13

1982-09-28

Wintercorn, Richard A.

Photocopying

Projection printing and copying cameras

Multicolor picture

355 71, G03B 2772, G03B 2776

Patent

active

043516084

ABSTRACT:
A lamphouse for use with an enlarger head in the production of prints on variable contrast or on conventional photographic material which consists in part of a light source from which light is directed to a fixed apertured plate. There is on one side of the apertured plate remote from the light source a composite filter, one portion of which passes light in one of two mutually exclusive wavebands and the other passes light in the other of the two mutually exclusive wavebands. The composite filter is moveably mounted in relation to the apertured plate so that in one position the light passing the filter is in all of one of the mutually exclusive wavebands and in the second position the light passing the filter is in all of the other of the mutually exclusive wavebands. In intermediate positions of the filter a varying mixture of light of the two wavebands is transmitted. Mounted with the composite filter is a light attenuating means to cut down the amount of light passed in one of the wavebands to that which the combination of light source and photosensitive material to be exposed is more sensitive so that prints of equal visual density are obtained by exposures of equal duration whatever the position of the composite filter is relative to the apertured plate. The light attenuating means may be for example a shaped mask or a neutral density filter.

REFERENCES:
patent: 2734435 (1956-02-01), Leonardi
patent: 3374706 (1968-03-01), Weisglass
patent: 3469914 (1969-09-01), Thomson

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