| 摘要 |
PURPOSE:To obtain a titled photographic emulsion of which the crystal grains are twin and which has a narrow grain size distribution, high sensitivity and less photographic fogs by passing the emulsion through an atmosphere wherein the pBr of the liquid phase is lower than a specific value in the stage of growing a seed crystal contg. the twin particles. CONSTITUTION:A seed crystal emulsion including twin particles contg. >=10% twin particles of 0.1-1.0mu, in the number of pieces, twin particles having 0.1- 1.0mu average grain size is obtd. by an ammonia, neutral or acidic method in the presence of protective colloid. Silver ion or halide ion or a soln. contg. silver ion is added to the emulsion at a gradually increasing rate of supply to grow the seed crystal contg. the twin particles. The emulsion is passed through an atmosphere wherein pBr is lower than 0.15 at the point of the time when >=2/3 of the total amt. of the silver used is added, whereby a silver halide crystal is prepd. |
