SUBJECTS OF MINIMUM CONTRAST views are usually of this class as well as flat surfaced subjects which have but little tone or color gradation and hence little actinic contrast, as for example the evenly toned tin type or ferrotype, the daguerreotype and also photographs which have little tone contrast and which are to be copied, as well as all subjects which are to be photo graphed for their texture alone (see plate X). Should however a photograph or any flat sur faced subject have a full tone contrast as nearly from white to black, such a subject must be classed as of normal or nearly normal contrast. Should the inherent actinicity of any subject differ to a considerable extent in its different areas, as the hair, face and dress in a portrait subject, no lighting whatever can make of it a minimum contrast subject.
Every worker who does not deviate from the use of the modern fast emulsions must have encountered certain kinds of subjects which it seems impossible to render with brilliancy or well separated tone steps, even when it is desired to do so. By giving thought it will probably be found that these are the minimum contrast subjects now being discussed, of which plate IV is a good example. (It is evident that an exterior
of minimum contrast would ordinarily be void of interest. The area of grass without flowers on the left of the plate represents such a subject.) From such subjects and with the emulsions mentioned, under-exposure with normal develop ment gives thin flat negatives while normal ex posure with normal development gives good density but little gradation. When it is con sidered that such a subject may easily have an actinic contrast between its brightest and dark est parts of only 1 to 2 and that the emulsion used has the capacity normally to render con trasts of probably 1 to 32, this tendency to flatness is not a matter of surprise. The won der is that the contrasty emulsions with the latitude as low even as 1 to 4 or 1 to 8 have not been utilized more for the reproduction of these subjects of little actinic contrast to which they are by their nature so perfectly fitted.