440 HANDBOOK OF PHOTOGRAPHY 



so that all parts of the paper, except that which is being exposed at the moment, are 

 protected from exposure; so that the exact position of each portion is determined and 

 under control. 



Many so-called montages are merely "paste ups" in which portions of several or 

 many prints are cut to shape and pasted together to form some sort of pattern. The 

 true montage is much more difficult to do. Often two negatives are printed so that the 

 print from one overlaps that of the other. There are other modifications. 



Correction of Distortion.— Hy tilting the easel upon which the printing paper is 

 placed for exposure, certain distortion occurring in making the negative may be 

 corrected. Conversely, distortion may be produced by tilting the easel when printing 

 from a normal negative. If the camera has been pointed upward when making a 

 photograph of a tall building, the lines of the building will converge toward the top. 

 If, now, the easel is so tilted that the lines of the image tencj to diverge toward the top, 

 the lines of the building in the print may be parallel and therefore neither converge or 

 diverge. 



If much correction is to be performed in this manner, the fact that one portion of 

 the paper is further distant from the lens than another must be taken into account, and 

 the nearer portion should be given slightly less exposure. 



By distorting the shape of the printing paper, as by holding the edges, or the center 

 away from the easel, queer distortions of various sorts may be effected. 



Processing Prints. — Development serves the same purpose in making positive 

 prints as in making negatives. The exposed silver halide must be converted to 

 metallic silver; then the unexposed silver must be disposed of so that the print will be 

 permanent. Developing formulas recommended by the manufacturers for use with 

 their papers may be depended upon to give excellent results. For consistent results 

 the processing conditions (temperature, dilution of stock solution, age of developer) 

 must be carefully controlled. 



Positive prints are usually developed at 70°r. and the temperature of the conven- 

 tional developers should not be allowed to vary more than a few degrees from this 

 temperature. Developer should be freshly made; exposure conditions should be 

 standardized. 



Theories of development will be found in the chapters on Development. In 

 this chapter only the more practical aspects of developing procedure will be 

 discussed. 



Contrast Control. — The contrast of a paper print depends largely upon the grade 

 of the paper that is employed. It also depends to some extent upon the conditions of 

 processing. This is particularly true of bromide papers. For highest contrast the 

 paper must be adequately exposed and fully developed. If, for any reason, a print 

 having less contrast is desired, the print may be removed from the developer before the 

 full density in the shadows has been attained. 



Prints taken from the developer before a minimum developing time (13^ to 3 min. 

 for projection papers) will lack contrast, lack detail in the shadows, and will be poor 

 in tone. Overexposure and underdevelopment produce flat prints of poor color. 

 Underexposure or overdevelopment is likely to produce fogged prints in which detail 

 and contrast are lacking. 



Exposure Latitude. — At one time it was felt that a desirable paper was one which 

 had a soft gradation (low gamma) with short development and a steep gradation 

 (high gamma) with a longer development. Such a paper would have the character- 

 istics of a negative emulsion, gamma increasing with increasing development time. 

 Such a paper had limited exposure latitude, for the same character of print, but gave a 

 supposed increase in latitude for taking care of negatives of varying degrees of con- 

 trast. Such a latitude was at the expense of print color. 



