HANDBOOK OF PHOTOGRAPHY 



making the negative. Essentially it is a lighttight box holding the negative film or 

 plates upon which the image is impressed. At the other end of the lighttight box 

 is the lens and focusing system. The shutter may be before, behind, or between the 

 elements of a complicated lens system, or in focal-plane shutters it may be immediately 

 next to the photosensitive material. In addition to these essential elements, the 

 camera is provided with a variety of semiessential and highly convenient features and 

 adjustments. These include focusing rack and pinion arrangements; methods of 

 aligning or misaligning the lens, with respect to the plate, for producing or eliminating 

 certain distortions; a ground glass or optical focusing system; provisions for deter- 

 mining the angle of view to which the film will respond; methods for quickly changing 

 from one plate to another; screwheads for attaching to tripod supports, view finders, 

 range finders, etc. 



The various types of work which are attempted make it desirable to put emphasis 

 on certain features, perhaps at the expense of other features, for specialized branches 

 of photography. For this reason a wide variety of cameras of different construction 



y Light from 

 Jighi- source 



Object 



Light reflected 

 from object 



'/mage of 

 object on 

 film or 

 plate 



Lens fp cusses image 

 of object on photo- 

 graphic plate 



Fig. 1. — Diagram of camera focused on object, ready for making a photograph. 



is available. Each of these has its own field of maximum utility, but no single type 

 of camera is ideally suited to all types of photographj^. Large studio-type cameras 

 with a wide variety of adjustments which can be made quickly and conveniently are 

 frequently used when large prints of high detail are required. But these cameras are 

 bulky. The miniature camera which has become so popular within the past decade 

 is admirably adapted to rapid-fire picture taking, is eminently suited to candid 

 photography. Its negatives are subject to deleterious effects of grain, scratches, 

 and other negative imperfections, as the print must be enlarged to be useful. Minia- 

 ture cameras do not have adjustments for eliminating angular or perspective distor- 

 tion. For photography in which action plays a large part, the reflex type of camera is 

 very popular since it enables the operator to view the subject up to the moment of 

 taking the picture, and to center properly the most important action. The focal- 

 plane shutters of these reflex cameras are sufficiently fast to stop motion where a 

 between-the-lens shutter could not be used satisfactorily. 



Developing and Fixing. — After the negative material has been exposed and the 

 latent image is impressed on it, it becomes necessary to develop and fix the negative 

 before it can be used to provide a print. The developing process is one in which 

 the silver halide grains which were exposed to light are reduced to metallic silver, the 

 process being carried on in the dark to prevent further exposure or fogging of the 

 negative material. The fixing process dissolves out the undeveloped silver halide 

 grains and leaves the metallic silver untouched. The fixed negative must be washed 

 to free it from the fixing solution, as otherwise the negative may turn yellow or brown 

 with aging. 



