516. Local Control During Printing. The effect of retouching or other work on the negative may sometimes be completed or supplemented by holding back the printing of certain parts of the picture.
If, when using a printing frame, a suitably shaped piece of cardboard is held in the hand at a little distance in front of the frame during a part of the exposure to light, its shadow will be thrown on those parts of the picture which it is desired to hold back. To prevent a sharp outline of the cardboard appearing on the print, it should be kept slightly moving to and fro, either in the same plane as the cardboard or perpendicularly to its own plane. 2 A frame with a translucent back has been used, so that the position of the shadow on the picture can be ascertained from the back of the frame.
517. Reducing Contrast and Definition. Be sides the methods already described in § 313 for obtaining prints with softened outlines, the following method can be used to reduce the contrasts to a slight extent of a large picture, and especially of a picture containing large dark areas with little detail. During the whole or part of the exposure to light, an embossed film, a piece of closely-woven muslin or net, or even a film negative of average density of a definite pattern is placed between the negative and the sensitive paper.
For printing negatives whose range of densi ties is greater than the gradation of the softest paper available, the negative can be doubled with a positive of suitable contrast (§ 444, foot note). In the particular case of silver develop ment papers, recourse may be had to the Sterry effect (§ 555, footnote) or to the Herschel effect (§ 571, footnote).
Besides the method of stylization already mentioned (pseudo-solarization, § 204), it has been suggested to limit as follows the scale of tones to a given number, say five, of grey tones (Isohelie). From the original negative the de sired number of copies are made on very con trasty plates, each with a suitable exposure. These intermediate positives are intensified so as to constitute almost silhouettes. Finally, these are copied on thin films in such a way as to have only very slight density, and these nega tives are then superimposed in register to form the ultimate negative (W. Romer, 1932).
18. Combination Prints—Insertion of Back grounds—Adding a Sky to a Landscape. It is not possible to consider here every case in which a photograph can be " faked" by the photo grapher, for example, by introducing a figure into a group or scene, or by inserting into a landscape a foreground from another negative. These combinations are always made by cutting out the parts of the print to be transferred, thinning the edges of the paper, and sticking them on the print of the group or landscape, concealing the joints by a little retouching and finally photographing the composite pic ture.
Three operations which occur relatively fre quently will only be considered here, viz., grouping of several portraits in one photograph, putting a background into a portrait, and adding clouds to a landscape.
For printing various portraits (the members of a family for instance) in desired positions on a single sheet of paper) made vignetted against a white background, a model on glass is made (as specified in § 855 for printing stereoscopic positives from separate negatives), and each of the negatives is fixed in suitable position on a glass of the same size as the desired photographs,. When printing, this glass support and the sensi tive paper (marked with pencil on the back to show the correct way) must be pushed up against the same corner of the printing frame or of the printing machine.
Film background negatives are sold which reproduce the standard types of professional backgrounds (draperies, cloudy backgrounds, various interiors) of which the central portion is either completely transparent or completely opaque. In the first case the masks are super imposed on a portrait negative which has been taken in front of a plain and very dark back ground, the background and the subject being afterwards printed at the same time. In the second case, after exposing the paper under the negative of a portrait taken with a uniform white background (or blocked out afterwards to hide a defective background), it is exposed under the background negative, suitably propor tioning the two times of exposure.