Abstract: A process for controlling the silver halide grain-to-grain distribution of a variable contrast dye in a light sensitive silver halide emulsion layer of a variable contrast photographic element, and thereby adjusting the low contrast characteristic curve of the element, is disclosed comprising the process steps of adding a green variable contrast sensitizing dye of the following formula (I) to a silver halide emulsion for a variable contrast photographic element, adding a blue sensitizing dye of the following formula (II) to the same silver halide emulsion, and coating the emulsion on a support. In the process, the green and blue sensitizing dyes are added to the emulsion at substantially the same time, and the green dye is added in an amount less than that required to impart maximum sensitivity to all of the silver halide in the emulsion. ##STR1## In formula (I), R.sup.1, R.sup.2, R.sup.6 and R.sup.

Abstract: A method for the reproducible production of nonuniform distributions of polymolecular association clusters, each of the clusters comprising a plurality of a species A in association with a single species B, is disclosed. Species A is preferably a photographic dye and Species B is preferably a silver halide particle. The method comprises: (a) mixing a suspension of particles of species B in a vessel; (b) flowing a portion of the suspension through an isolated reaction zone; (c) introducing species A into the isolated reaction zone; and (d) returning the portion of the suspension including the introduced species A to the vessel. In another aspect, the invention relates to an apparatus for carrying out the foregoing process.

Abstract: Photographic silver halide emulsions are disclosed comprised of radiation sensitive silver halide grains exhibiting a face centered cubic crystal lattice structure internally containing a carbonyl coordination ligand and a transition metal chosen from groups 8 and 9 of the periodic table of elements.