Huntington] NATURE PHOTOGRAPHY 173 



and that the nearer the camera is to the object the farther the 

 bellows will need be extended, and vice versa. 



Having focused the image satisfactorily on the ground glass, 

 decrease the diameter of the diaphragm until its pointer is at F 1 1 

 or U. S. 1 6 (depending on which scale is used), close the shutter, 

 introduce a loaded plateholder unto the back, and withdraw the 

 slide next the lens from the plateholder. Everything is now ready 

 for the exposure, the length of which should vary with the plate 

 used, the time of day, the time of year, the condition of the light 

 (whether cloudy or bright) and the nearness to the object. Let us 

 assume that it is a fairly bright day, somewheres between o a. m. 

 and 4 p. M., in March, that the distance from the tree is over 50 

 feet, and that Cramer's Medium Isochromatic plate is being used; 

 the exposure should be between two and five seconds. The writer 

 recommends that three plates be exposed, one, three, and five 

 seconds respectively, from the same point and the resulting nega- 

 tives be compared. Good results may be obtained from a much 

 shorter or somewhat longer exposure. The times of exposure 

 given in the tables issued by camera and plate makers are mini- 

 mum, and need be short if moving objects are to be photographed, 

 but the best results are to be obtained from long time exposures. 



The slide should be returned to the holder with the dark edge 

 outward (to indicate that it has been exposed) and the holder with- 

 drawn from the camera. 



The three plates may now be developed in a dark room (light- 

 tight) illuminated with a faint ruby light. The writer recommends 

 the use of Eastman's Hydrochinon developer which may be bought 

 in powders but many other developers such as metol-hydrochinon 

 will also give good results, and are preferred by many photog- 

 raphers. The powders should be dissolved according to direc- 

 tions, and poured into a freshly washed tray (6x8 inches is a con- 

 venient size) . A tray of acid hypo (fixer) , dissolved according to 

 directions on the package, should also be at hand, as well as a tray 

 of clean water. 



A single plate should be placed in the developer, emulsion side 

 up, and quickly covered with the developer fluid; it is well to 

 wipe the surface of the plate with a wad of absorbent cotton wet 

 in the developer to insure complete contact with the developer. 

 The tray should be rocked for the first minute; the image soon 

 appears, and development is continued until the high lights of the 



