Abstract: A silver halide photographic emulsion containing a spectrally sensitizing amount of a sensitizing dye represented by the general formula (I) ##STR1## and a sensitizing dye represented by the formula (II) ##STR2## wherein Z.sub.1 and Z.sub.2 each is an atomic group necessary to complete a benzoxazole ring or a naphthoxazole ring; R.sub.1 is an alkyl group or an allyl group; R.sub. 2 is an alkyl group or an allyl group; R.sub.3 is an unsubstituted lower alkyl group, a hydroxyalkyl group or a carboxyalkyl group; R.sub.4 is same as R.sub.1 ; R.sub.5 is an alkyl group, an allyl group or a phenyl group; R.sub.6 is an alkoxycarbonylalkyl group, a hydroxyalkoxyalkyl group, an acyloxyalkoxyalkyl group, an N-(N,N-dialkylaminoalkyl)carbamoylalkyl group, an N-(N,N,N-trialkylammonium)carbamoylalkyl group or an N,N,N-trialkylammoniumalkyl group; X.sup.- is an acid anion; and n is 0 or 1.

Abstract: A silver halide photographic emulsion containing the combination of (i) at least one cyanine dye wherein two basic 5-membered and/or 6-membered nitrogen-containing heterocyclic nuclei are linked by methine groups having an odd number of carbon atoms not exceeding 7 and the substituents on the nitrogen atoms in the heterocyclic nuclei are aliphatic groups or aromatic groups with at least one of the substituents on the nitrogen atom being an alkyl group having a sulfo group or a carboxyl group, and (ii) at least one substantially colorless nitrogen-containing heterocyclic organic base selected from the group consisting of a benzothiazole, a benzothiazolone, a naphthothiazole, a naphthothiazolone, and a quinolone in a quantity sufficient to supersensitize.

Abstract: A method for spectrally sensitizing a photographic light-sensitive emulsion, which comprises dissolving a photographic spectrally sensitizing dye having an amidinium ion auxochrome in an organic solvent containing a substantially water-free acid having a pKa not exceeding about 5, and adding this dye-containing acid-organic solvent solution to a light-sensitive emulsion.

Abstract: A silver halide photographic emulsion containing a supersensitizing amount of the combination of at least one dye represented by the general formula (I) ##SPC1##wherein Z represents the non-metal atoms necessary to form a benzene nucleus; R.sub.0, R.sub.1 and R.sub.2 each represents aliphatic groups, with at least one of R.sub.1 and R.sub.2 representing an alkyl group containing a carboxy group or an alkyl group containing a sulfo group; Y represents a halogen atom; X represents an acid anion; n represents an integer of 1 to 2, with n being 1 when the dye forms an intramolecular salt; and at least one dye represented by the general formula (II) ##EQU1## wherein Z.sub.1 represents the non-metal atoms necessary to form a 5-or 6-membered heterocyclic nucleus; Q represents the atoms necessary to form a rhodanine nucleus, a 2-thio-2,4-imidazolidinedione nucleus, a 2-pyrazoline-5-one nucleus, or a 2-thio-2,4-oxazolidinedione nucleus; R.sub.3 represents an aliphatic group; R.sub.