| 摘要 |
1471778 Photographic silver halide element E I DU PONT DE NEMOURS & CO 22 Aug 1974 [27 Aug 1973] 36956/74 Heading G2C A photographic element having wide exposure latitude and low gradient is made by (a) dividing a single silver halide emulsion into a first portion and a second portion, the portions being of identical silver halide grain size and composition, (b) chemically and optically sensitizing the first portion while optically sensitizing the second portion and either not chemically sensitizing the second portion or chemically sensitizing it to a lesser extent than the first portion, so that the two portions will differ in speed, and then (c) either recombining the portions and coating them as a single layer on a film support, or coating them as separate layers on a film support. The optical sensitization may be effected using the same dye at the same concentration for each portion and the dye may be a panchromatic sensitizer. The element may be used for making masks for colour separation prints for use in colour printing.
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