A PRACTICAL ANALYSIS OF SUBJECTS It has undoubtedly occurred to many readers that the classification of white and black and the different colors as to their inherent actinicities is a refinement seldom necessary in practice. The purpose has been to establish in the mind of the reader a true conception of actinicity as a quantitative value pertaining directly to all sur faces. In practice, however, should a white and black cloth be stretched flat and be photo graphed separately with a normal exposure on the basis of their respective actinicities, it would probably be somewhat difficult to distinguish the photographs from each other, supposing that the cloths be of like texture. As to tone, such a result could not be spoken of as a "natural" rendering since by varying the depth of printing, a light or a dark print could be made at will from either negative. On the contrary, should the two cloths be photographed side by side in the same picture, the exposure being given on the basis of the actinicity of the white one, then, should the emulsion have considerable latitude, each cloth would be represented in its proper position as to tone.
This brings the reader back to the considera tion of the "dominant," "objective," or brightest part of a subject and its importance in the actinic analysis of subjects and emphasizes anew the importance of knowing the actinic gradation of a subject throughout and the agreement of the latitude of the emulsion with that gradation. For example had the plate used in the above case had a latitude of only 1 to 8, it is clear that the white and the black cloth could not have been properly photographed in the same picture by purely normal exposures on the basis of the white, since their actinic contrast is at least 1 to 16 and with such an exposure the intensity of the black cloth could not have overcome the inertia of the emulsion.
Should one be photographing a somewhat open view of the mid-distance class, and the sky be considered as the maximum point and its intensity be taken as the basis of exposure, a white and a black horse in the mid-distance would each assume its proper place in the tone gradations of the picture, always providing of course that the work of developing, etc.,
be performed properly. On the other hand should it be desired to obtain a perfect photo graph of each of the horses separately and of good size in the picture, the black one should actually have about four times the exposure required for the white one, although the actin icity of the former is only about A that of the latter. It is obvious that the image of a black object should overcome the inertia fewer times than that of a white one since its tone in any picture should naturally be darker than that of a white object.
In studying nature from the view point of practical photography it is convenient, as has already been explained, to divide all subjects into two general classes: those whose actinic gradations are created by nature and which must be photographed as found or be modified by the selection of view point or lighting, as by choosing a time when the sunlight is modified by a cloud or when it shines upon the subject from a desired direction. The other class con sists of those subjects which by their nature are almost wholly in the worker's hands and whose gradations therefore must, or should be, wholly arranged by him (p. 87, 102, 141).
Out door subjects are naturally of the first class since the sun and sky cast their light over nature in their own way and we can only select as already explained, the conditions of view point and the time of day when the lighting pleases us most.
As helps in composition or pictorial construc tion it is necessary to distinguish between subjects of the foreground, mid-distance and distance class. Subjects of the distance class are usually spoken of as bird's eye views and their characteristic is that they have no near objects whatever in them and little else besides a horizontal or rolling expanse of grass or earth, or what would be in view when looking down from a somewhat high point as in overlooking a valley. A mid-distance view is one which has some objects in it but of such size that their images would not fill more than about one fifth of the dimension of the plate in either direction on being photographed.