The Sharpness of Photographic Materials

The sharpness of a film must be estimated for the particular conditions of use: the limiting performance for either high or low contrast objects at high magnifications may be described satisfactorily by the resolution figues; the sharpness of larger images may be expressed conveniently in terms of the image width just showing some loss of density, but because local developer exhaustion effects occur almost universally, it is necessary to use a form of test chart similar to the type of image to be photographed.