Ciba-Geigy Ag

Jean-Francois Reber

Rolf Steiger

Geoffrey E Ficken

Aaron David Ezekiel

Photographic negative material which has at least one layer which contains a desensitized silver halide emulsion, the desensitizer used being a trinuclear heptamethinecyanine or a halogenated trinuclear tetramethinecyanine which has three identical heterocyclic ring systems, which can have different substituents and are linked to one another by three identical methine systems, which can be mesomeric, is suitable for processing in subdued daylight but nevertheless has an adequate sensitivity on exposure to intense light.

Photographic negative material with at least one layer containing a

The present invention relates to light-sensitive photographic material with a light-sensitive heavy metal compound, e.g. a silver halide, and a spectral sensitizer. The spectral sensitizer is a compound in which the radicals of a sensitizing dyestuff are covalently bonded to amino, imino, hydroxyl, mercapto, carboxylic acid or carboxylic acid amide groups of a natural hydrophilic colloid, preferably gelatin. The invention also relates to new sensitizing dyes which are dinuclear cyanine dyes or merocyanine dyes which have attached either to a heterocyclic nucleus of the dye or to its methine chain a group which is reactive with a hydrophilic colloid.

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Marly, Switzerland

Jean-Francois Reber