This section is from the "Studio Light Incorporating The Aristo Eagle - The Artura Bulletin 1913" book, by Aristo Motto. Also see Amazon: Studio Light Incorporating The Aristo Eagle - The Artura Bulletin 1913.
The best plate for photographic portraiture is the one which is capable of rendering the greatest number of tones, and which, when properly exposed and developed, has registered every tone of light and shade in its proper relation.
A perfect negative is one in which all values are in proper relation to one another and which, both in its color and gradation, is such that every one of its values may be printed without the necessity of dodging, after the negative has reached the printing frame.
It is not an easy task to reproduce from a solid round object, an image, on a flat surface, that will appear in its true form to the eye, both in correct perspective and gradation of light and shade, and in order to do so it becomes necessary to crowd as many tones as are possible between the two extremes of white and black, both of which must be used sparingly, whether the picture is represented in a high or low tone. To secure this effect of roundness one must necessarily begin with proper lighting, followed by the use of plates which are capable of registering the greatest number of tones, and a printing paper which will record every tone possessed by the negative.
In other and perhaps simpler terms, brilliant lightings with powerful gradation in connection with soft working plates and printing papers, will yield results which are far superior in quality to the soft or comparatively flat lightings, which are purposely made to favor contrasty plates or papers. This latter method is often adopted with the mistaken idea that the same effect will result. It is impossible to produce more quality in a negative than is in the lighting, or to expose and develop more gradation than the plate is capable of recording.
Let us suppose for example that we make up a portrait lighting composed of thirty tones, or halftones, and with each tone properly distributed. The first tone represents the strongest point of highlight and is placed with pure light from a north sky, the lower lights being graded and distributed with a dark screen placed near the subject and between the subject and the light.
The last tone represents the deepest shadow, the lower tones being graded and balanced by the use of a soft grey (instead of a white) reflector. We note that we now have a lighting covering a wide range, with an even and well balanced gradation - have roundness.
A plate which is capable of registering this range of tones and is especially capable of separating the more delicate tones of the higher lights, is exposed sufficiently to register the lowest halftone in the shadows and is developed to a density which represents a relative key in which the lighting was made - the lighting as you saw it on the ground glass. The result is a bold, vigorous negative, full of detail and gradation, from its strongest light to its deepest shadow, with wonderful roundness. See illustration A.
Suppose that with the same lighting a plate possessing a scale of only twenty tones is used. Again sufficient exposure is given to produce proper detail in the shadows. We readily note that ten tones are blocked or sacrificed, either in highlights or shadows or both. One may remove those ten tones in lighting, by diffusion of highlights or reflection in shadows, but just that much quality will be lost in the modelling.
It is true that a lighting which has overtaxed the gradation of a plate may be handled to some advantage by adjusting the developer to best suit the condition, but the fact that the plate is developed to prevent glassy shadows and chalky highlights, does not mean that those ten tones were registered - they were lost between the strongest lights and deepest shadows, and the result is an arbitrary scale of gradation. See illustration B. Of course, the plate with thirty tones will do just as much with a lighting of twenty tones, as the plate with a shorter scale, but it will also do more. A piano with only six octaves will do the same work as one of eight octaves, so long as it is not put to the test of rendering music which is written in more than six octaves.
The next essential is a printing medium which is capable of recording every tone possessed by the negative, and this again requires a paper with an abundance of gradation. The portrait to be one which is true in its likeness, must have a full complement of tones ranging from white to black, and without chalk or soot.
Such portraits are recognized by the initiated as works of a high order of quality and are accepted by the uninitiated with much favor, providing, of course, that the expression and posing have been properly managed.
Aristo Platino Paper is capable of handling many tones and requires for its best results, negatives which are vigorous, brilliant and powerful in gradation. In the early days of developing papers, they were lacking in gradation to such an extent that it was impossible to render a good print on them from the best of Platino negatives. These papers, at that time, required a very soft, flat negative with little gradation, such as most any plate will render, and photographic quality suffered through a lack of good modeling, which the operator did not dare put into the negative, since the paper would not reproduce it. Time and experience have again corrected this and the best gaslight papers are now improved to such an extent that they require, for the best results, negatives such as were made for Platino.
There are other advantages in the use of plates and papers permitting of bold lightings. Screens and shades used for modeling are much more effective under a clean, pure light, and exposures are shorter.
Seed plates, pyro developer and Artura paper form a combination that will give the whole gamut of tones - contrast without steepness - snap without harshness. With them you are not driven to the necessity of flat lightings to get softness. You can obtain vigor in the negative and roundness in the print, with nary a harsh line or clogged shadow.
It's a Seed Plate you need.
A. Seed Plate, brilliant lighting, full gradation. The Result - Roundness.
B. Another plate, with short gradation, same lighting. Exposure And Development - The Result - Harshness.
From An Artura Iris Print By The Kidd Studio. Roanoke, Va.