426 HANDBOOK OF PHOTOGRAPHY 



A very thorough and practical treatise on methods of printing on various papers, 

 of methods of measuring the contrast of negatives, and of measuring the capabiUties 

 of printing papers will be found in Dutton's book, "Perfect Print Control," The 

 Galleon Press, 1937. 



Storage of Printing Papers. — Papers should be kept dry and free from chemical 

 fumes, and from hypo dust. Preferably they should be stored in a cool place and 

 under a certain amount of pressure to keep them flat. If they are in a moist warm 

 atmosphere, they will mildew and stick together, being ruined for future use. Mois- 

 ture seems to be able to penetrate numerous thicknesses of protective paper as well as 

 the double envelopes in which most papers are now packed by the manufacturer. The 

 only solution is to keep printing papers out of a humid hot atmosphere; or to place 

 them in a simple drying closet which may be made by placing the paper in a box or 

 cabinet in which an electric light bulb burns continuously. Of course, the paper must 

 be protected from light if it is not to become fogged or exposed. 



Contact Printing. Comparasion of Contact and Projection Printing. — The ultimate 

 in sharpness of detail will only be secured by contact printing. When sharp negatives 

 are enlarged a matter of two to four times this lack of definition is not noticeable, but 

 in greater magnifications than these values the loss of sharpness is unavoidable. 

 Therefore, for extreme detail as for engineering or scientific record prints or where 

 reproduction by a photoengraving method is to be followed, the 8- by 10-in. contact 

 print on glossy paper, well ferrotyped, cannot be equaled. 



For portraits and pictorial subjects, however, there is often an advantage in a 

 projection print which is not so sharp as a contact print. In projection it is possible 

 to reduce still further the sharpness by the employment of diffusion attachments on 

 the enlarger lens or by making the exposure onto the printing paper through sUk or 

 other diffusing material. 



Only by projection may the final print be smaller or larger than the negative. For 

 this reason, if a very large print is desired, it is practically impossible to get it in any 

 other way than by projection. In commercial studios the 8- by 10-in. camera is almost 

 the upper limit of size in general use. Of recent years there has been a remarkable 

 trend toward smaller cameras, which are easier to operate, to move about, and which 

 have lenses of greater depth of focus. 



The miniature camera, with a lens of large aperture and short focal length has 

 made it possible to make photographs with very great depth of focus and very short 

 exposures. Negatives made in such cameras may be enlarged many times before 

 grain inherent in negative emulsions becomes annoying and before the natural loss of 

 definition with enlargement causes the print to suffer too much. Modern fine-grain 

 materials processed according to fine-grain technique will yield enlargements of 10 

 diameters^ before either grain or loss of detail becomes serious, and even greater 

 enlargements are possible if the utmost in detail is not necessary. 



There is little or no opportunity for dodging or holding back a portion of the nega- 

 tive in contact printing; in projection, dodging is very frequently employed. In this 

 manner emphasis may be placed upon the part of the image that merits it; details not 

 wanted may be subdued. The photographer is freed, somewhat, by this expedient 

 from the vagaries of uneven lighting. 



Negatives which are to be enlarged must be handled with great care. The com- 

 mercial photographer, accustomed to making contact prints from an 8- by 10-in. 

 negative must learn an entirely new technique if he hopes to turn out good prints from 



1 Two terms are used for indicating the magnitude of the enlargement: diameters and the general 

 term magnifioation. Strictly, the latter term should indicate the enlargement in area. Practically, 

 however, all enlargements are rated as the number of times any linear dimension is increased. Thus a 

 10 times (diameter) enlargement means that, for each inch of the negative along a side, the print 

 will be 10 in. 



