A process of preparing a radiation sensitive high chloride high aspect ratio tabular grain emulsion is disclosed wherein silver ion is introduced into a gelatino-peptizer dispersing medium containing a stoichiometric excess of chloride ions a chloride ion concentration of less than 0.5 molar and a grain growth modifier of the formula: ##STR1## where Z.sup.2 is --C(R.sup.2).dbd. or --N.dbd.;Z.sup.3 is --C(R.sup.3).dbd. or --N.dbd.;Z.sup.4 is --C(R.sup.4).dbd. or --N.dbd.;Z.sup.5 is --C(R.sup.5).dbd. or --N.dbd.;Z.sup.6 is --C(R.sup.6).dbd. or --N.dbd.;with the proviso that no more than one of Z.sup.4, Z.sup.5 and Z.sup.6 is --N.dbd.;R.sup.2 is H, NH.sub.2 or CH.sub.3 ;R.sup.3, and R.sup.4 and R.sup.5 are independently selected, R.sup.3 and R.sup.5 being hydrogen, hydroxy, halogen, amino or hydrocarbon and R.sup.4 being hydrogen, halogen or hydrocarbon, each hydrocarbon moiety containing from 1 to 7 carbon atoms; andR.sup.6 is H or NH.sub.2.