2IO 



FOCUSING IN PHOTOGRAPHY 



[Ch. VII 



If one has a good place to do the work in, the light can usually be 

 arranged satisfactorily with the object in a vessel with a proper 



background in the bottom. If not, a double 

 stage must be used, as shown in fig. 126. 



If white embryos or other light objects 

 are to be photographed a black background 

 is best. This is produced by using black 

 glass on the bottom of the dish. Or if no 

 black glass is available, some smooth paper 

 is coated with waterproof India ink and al- 

 lowed to dry. This gives good contrast. 



With a proper background make sure that 

 the lighting is such as to bring out the de- 

 sired details. Turn the object in various 

 positions till the desired one is found which 

 shows clearly the points that are to be em- 

 phasized. 



§ 333. Focusing stand for the vertical cam- 

 era. — To hold the specimen and to provide 

 for the finest focusing, and also some of the 

 coarse focusing, a modified microscope stand 

 is convenient. It has no tube, but two stages 

 are attached to the support usually carrying 

 the tube. This then can be raised and low- 

 ered by the coarse and by the fine adjust- 



Fig. 126. Vertical 

 Photographic Camera. 



T Low table 50 cm. 

 high, 50 cm. wide, and 70 

 cm. long. 



Fs Focusing stand 

 with vessel for holding ment > as m focusing the microscope, except 



embryos and small ani- here the stages move, the photographic ob- 

 underUquid. ° t0grap e jective remaining stationary (fig. 126). With 

 VC Vertical camera the rod to hold the camera at a fixed ex- 



with an objective (ob.) in 

 the lower end and a fo- 

 cusing glass (fg) above. 

 (See fig. 107 for fuller de- 

 scription.) 



tension, most of the focusing can be ac- 

 complished by sliding the whole camera up 

 and down the vertical graduated support 

 (fig. 126). 



§ 334. — Focusing glass. — There are two ways of using this: 

 1. A clear screen is used instead of aground-glass. On this is a 

 diamond scratch in the middle. The focusing glass is carefully 



